Psychic Awakening
The Psychic Awakening is the name of an event in the Warhammer 40k timeline, taking place during the Age of the Dark Imperium. The Galaxy, split asunder by the Great Rift, sees basically every faction in the galaxy affected in some way, either by a sudden influx of newer, powerful psykers, or by political and cultural changes as the events of the Age of the Dark Imperium causes shakeups in the status quo.
Yes, that's right, GW seems to be Advancing the Storyline, with Psychic Awakening following a similar narrative event that occurred earlier in 2019, the War of Beasts (aka Vigilus Defiant / Vigilus Ablaze).
There are rumors that Psychic Awakening will be followed -- or will be released alongside -- a new "8.5 edition" with the main rulebook being updated, as it is 2 years out of date now. In addition, there are rumors of "Codex 2.0" releases, with this being propped up perhaps in part by the Space Marines codex refresh that launched right around the time that Psychic Awakening was announced as well as the Chaos Space Marines codex released around the same time as Vigilus Ablaze. Each book effectively gives rules update to each of the factions featured in it, for example Tyranids being given the "build your own hive fleet" rules that the Space Marine successor chapters had. Codex 2.0 compiling these updates is likely.
Regardless of "8.5" or "Codex 2.0," GW has confirmed that there will be new rules for each existing faction, with "Each psychic Awakening expansion [focusing] on a different war zone," with each book having fluff and rules updates "for at least 2 factions." This suggests at least one of the books has only two factions, and with GW considering, say, Dark Angels and Blood Angels to be two different Factions, we could see upwards of 11 books out of this. GW has further clarified at Open Day 2019 that the general plan is to add one "reborn, reimagined, (or) brand-new" character for each book (or faction), which they have generally stuck to so far.
The first announced war zone, Phoenix Rising, covers the Eldar undergoing a minor civil war -- the Ynnari having broken the balance between the Craftworld and the Dark Eldar, resulting in all three sides kicking each others' asses.
This style of narrative updates and a somewhat stable core set of rules with updating codexes would put 40k roughly similar to the model that GW is using for AoS, for good and bad. (Mostly good.)
Factions
The updated Race Icons sheet lists 24 factions. As of The Greater Good (Jan 2020), 10 factions have seen PA updates with 7 coming soon.
- Space Marines (Faith and Fury)
- Chaos Space Marines (Faith and Fury)
- Eldar (Phoenix Rising)
- Dark Eldar (Phoenix Rising)
- Harlequins
- Inquisition/Deathwatch
- Grey Knights (Ritual of the Damned)
- Talons of the Emperor - Custodes + Sisters of Silence
- Thousand Sons (Ritual of the Damned)
- Death Guard
- Genestealer Cults (The Greater Good)
- Imperial Guard (The Greater Good)
- Imperial Knights (Engine War)
- Chaos Knights (Engine War)
- Orks (Presumed: Saga of the Beast)
- Necrons
- Tau (The Greater Good)
- Chaos Daemons (Engine War)
- AdMech (Engine War)
- Blood Angels (Blood of Baal)
- Sisters of Battle (Faith and Fury (sort of))
- Tyranids (Blood of Baal)
- Space Wolves (Presumed: Saga of the Beast)
- Dark Angels (Ritual of the Damned)
Phoenix Rising
The Aeldari are a psychically sensitive race, and the fragile balance between these disparate cultures has been disturbed by the Psychic Awakening. These factions have become embroiled in a full-scale internecine war for the future of their people.
Phoenix Rising is the first listed event listed as part of the Psychic Awakening and focuses on how the Great Rift has made things harder for the Aeldari -- the Asuryani, the Drukhari, the Harlequins, and the Ynnari. Among other events, we have Drazhar deciding that a Phoenix Lord's head would look good in his trophy room and settling on Jain Zar to be the lucky donor, but the main focus is on the Ynnari, as Slaanesh moves to thwart their attempts to awaken the God of the Dead. Yvraine learns that the final Cronesword is in Slaanesh's clutches and just barely survives a confrontation with the Keeper of Secrets Shalaxi Helbane - only to learn that the daemon was holding back just to fuck with her.
This is a boxed set that is providing new Plastic Howling Banshees, including a maskless Exarch -- a Ynnari Howling Banshee Exarch, "for they walk a very different path to their Craftworld cousins", as well as a new plastic Jain Zar. We will also get new Drukhari models and rules in the form of the Incubi along with Drazhar, though they don't seem to have any new wargear or rules for the Klaivex. Also included with the set are some new Hellions and Scourges, as well as three transports: A Falcon, a Vyper and a Venom. Alongside the campaign missions, this will also include new "Successor Chapter"-like rules that let you piecemeal together new properties for custom Craftworlds, Kabals, Wych Cults, and Covens.
Faith & Fury
The Sisters of Battle and Astra Militarum – bolstered by a massive strike force of Adeptus Astartes led by the Black Templars – stand firm in their creed to defend Humanity, at any cost...
As part of GW's reminder that Sisters of Battle exist, Faith and Fury sees Kor Phaeron of the Word Bearers, alongside members of 5 other Chaos Space Marine legions, attacking the Talledus system, a region of great importance to the Ecclesiarchy on account of its ties to Sebastian Thor. Defending Talledus is the Sisters of Battle, the Black Templars, the Salamanders, the White Scars, and the Imperial Guard, although this is not the Imperial Guard's book.
Content includes updates for the Black Templars (who were not included in the Imperial Fists Supplement of the 8.5 Marines Codex), "Chapter Litanies" and updates to Space Marine "Heroes" (such as Chaplains or Librarians) allowing them to take new relics and warlord traits with the use of a specific Stratagem, as well as updated rules for the Word Bearers, Night Lords, Alpha Legion, Iron Warriors, Emperor's Children, and World Eaters. New model releases include a new Chaos Space Marine Sorcerer.
Fluff updates include the Word Bearers trying to corrupt Imperial Cults only to see the Great Rift's energies causing weird shit like Flocks of Golden Eagles or Pillars of Golden Flame to appear, which restore faith in the Emperor when they're seen -- basically, Chaos no longer has a monopoly on warp fuckery, pious Imperials can do it too, now. This culminates during the battle of Talledus when "golden faced spirits" are summoned out of the Sisters of Battles tombs, creating a shield that instantly burns any demon that touches it to ash while also repairing the walls of the immaterium (de-Chaosifying the area, like a Blank) and generally screwing Kor Phaeron over, leaving him looking stupid and calling for reinforcements.
This is further expanded upon in a collector's edition exclusive chapter that covers the Alpha legion turning an entire planet of normal humans instantly into Psykers, except their faith causes them to summon the aforementioned "good warp stuff" like flocks of golden eagles and the like, as well as the Emperor Angelic, a psychic manifestation of the Emperor that promptly fucks the Alpha Legion up. The psykers on the planet are also turned into Emperor-empowered super-psykers called the "Humble Saints" which can nuke the Alpha Legion's psykers and daemons with a wave of their fingers. But because it's still Grimdark, the Iron Hands demand these new psychic superhumans be purged and call in the Sisters of Silence and Inquisition to do so when the Sisters of Battle refuse to let them.
tl;dr: The Word Bearers discover that Imperial Faith is now summoning their own warp entities -- Golden Eagles, Pillars of Golden Flame, Golden Faced Saints, and a psychic manifestation of the Emperor himself. The Alpha Legion has a way to turn normal humans into Psykers en mass, except Chaos no longer has a monopoly on psykers.
Blood of Baal
In these dark and desperate times, far from the guiding light of the Astronomican, only heroes such as Commander Dante, Mephiston and Gabriel Seth of the Flesh Tearers were able to hold the defenders of Baal together.
Blood Angels vs. Tyranids, Round 2. Hive Fleet Leviathan may have been sent reeling with the Great Rift's opening, but they still held a great many key locations that the sons of Sanguinius needed. Even more troubling is that there are an increasing number of psykers appearing within the local region, (uncollected thanks to the Black Ships vanishing) and their interaction with the Shadow in the Warp is triggering strange psychic phenomena that appear to be strengthening the Tyranids. Dante and (now Primaris) Mephiston lead the chapter to the funeral world of Kheru to oust the nids from there before they eat up everything, Seth and his chapter go to the industrial world of Ashallon and get reamed until they slay the psychic beacon on the planet.
Rules-wise, this granted the Blood Angels the tools that the 8.5 Marine codex has, making them even more of a chapter of walking blenders, with the Flesh Tearers gaining a few tools as well. The Tyranids, on the other hand, get to ride the "Custom Hive Fleet Rules" train that proved wildly popular elsewhere alongside a bundle of other rules to keep up with everyone else and a new "Adaptive Physiology" ability that lets them add a Warlord Trait equivalent to a generic infantry squad or monster. Model-wise, a new Primaris Mephiston accompanies this release.
Ritual of the Damned
From the boiling bowels of the warp, the Planet of Sorcerers has vomited forth into realspace. [...] Magnus the Red, Sorcerer King of Prospero, seeks to bring about the ruination of Mankind. [...] We must halt this ritual of the damned.
Thousand Sons, Dark Angels, and Grey Knights. Magnus is back from his trip to the Webway, and he's gathering tons of psykers for a ritual to rapidly accelerate the rate at which humans are becoming psychic. Thus, Dark Angels and Grey Knights are sent to foil the ritual. They are able to disrupt it, but it is only a matter of time before the Crimson King can attempt it again and in the meantime the Thousand Sons' attacks on the Imperium have grown even more intense. The action takes place around Sortiarius, with the trailer showing a massive Imperial fleet going towards the Planet of Sorcerers. This time, the new model is Master Lazarus - previously a Dark Angels Sergeant, he's been promoted to Captain of the 5th Company and undergone the Rubicon Primaris after the events of Wrath of Magnus, incidentally making him the first Primaris to become part of the Inner Circle.
Rules-wise, this book grants the Dark Angels the new shiny Primaris toys from the 8.5 Edition Space Marine Codex, as well as rules for the Deathwing and Ravenwing, while the Grey Knights gain a new ability - Masters of the Warp - if they take a dedicated army of Grey Knights. Will this see the Grey Knights actually fixed? Unlikely, but faith in the Emperor is it's own reward. As for the Thousand Sons, they can now dedicate their army towards one of nine Cults of the Legion in a move reminiscent of their Horus Heresy equivalent.
The Greater Good
This is O’Shaserra speaking. I hope this message arrives in time for you to be warned. In time for you to act.
The Tau, facing the wormhole they accidentally created in the Fourth Sphere Expansion alongside the human-hating, xenophobic Fourth Sphere remnants, continue to expand into the Chalnath Expanse. It isn't long until the Fifth Sphere's expansion is interrupted by reports of something they weren't aware of -- corrupted, mutated Gue’ron’sha swarming the Startide Nexus, beating the Fifth Sphere navy back. Calling themselves the Death Guard, the Tau have no idea what they are facing, although they're learning very quickly indeed.
At the same time, Grezum, a planet the Tau are infiltrating with their Greater Good indoctrination, has a Genestealer cult called the Mindchord rebelling at the same time. And let's not forget the Imperial Guard trying to fend off both the Tau and the Genestealers and trying to desperately keep the region under control.
Part of the fun of the fluff released so far is the Tau's complete cluelessness about the danger that this strange "Nurg'hel" creature and his Gue’ron’sha army represent; lets also not forget that the Tau have intentionally infested one of their own worlds with a Genestealer Cult infestation to see what would happen, which may have infected an Ethereal. The new model this time around is Commander Shadowsun, equipped with a newer variant of her battlesuit.
Rules wise, the Imperial Guard, Tau and Genestealer Cults all received new stratagems, wargear and got to join the custom Guard Regiment/Tau Sept/Cult Creed club. It also included rules for several Militarum Tempestus regiments - including new relics, stratagems and even regimental doctrines for six of the most famous regiments, essentially making them their own faction.
You might have noticed that despite being featured in their promo material and background lore, the Death Guard are notably absent from the rules and lore, and that's because they're not really in the book. GW's not ruling out featuring them in a later book, but given what we know about those so far, it doesn't seem like they'll be getting anything new anytime soon.
Saga of The Beast
Probably Space Wolves, since sagas are their thing, but definitely Orks. New model this time around is Makari, who apparently got better after being sat on. Oh, and Ghazghkull Mag Uruk Thraka.
Engine War
AdMech, Daemons, and both flavors of Knights. AdMech are getting Serberys Raiders, cyber-horse riding cowboys that come in Ranger and Vanguard flavors, the Archaeopter, a new ornithopter-like vehicle (with gunner / bomber / transport options), and the Pteraxii, a Jumppack version of the Sicarians (which appear to come in Ruststalker and Infiltrators variants). No other information known yet.