This makes perfect sense, given that AHS creator Ryan Murphy announced in June that Season 8 would be a crossover season between Murder House (Season 1) and Coven (Season 3).
Murder House, of course, had strong ~apocalypse vibes~...
...ending with Michael — Tate and Vivien's son, aka the Antichrist — murdering his nanny.
Is Michael the red baby in the promo images?! What's the connection between Murder House and Coven?! Will the world actually end?! Only time will tell.