The new codex for the Grey Knights is out, and it tells the Terminus Decree. I read about this right before the License to Buy a Pizza thread, so all I could see was Orks. Apparently the decree says that if the Emperor stands up from his throne, is reincarnated, or ascends to godhood, the grey knights must stop this. There's hints that the emperor is already reborn against his will, and doesn't even know what or who he is yet. So a new story is building up.
I haven't found any news about it, only YouTubers and random reddit threads. This is coming at the same time that Space Marines are no longer male.
I guess I should mention this is WarHammer 40k stuff.
See also, the very noticeable absence of almost all modern lore in the new games.
The Rogue Trader RPG is 95% lore from twenty years ago back when Dark Heresy was still in print, and the newly announced sequel just straight up is Dark Heresy.