The new 7.3 PTR has just been announced, with a new raid, and dungeon. This is a similar thing from the 7.2 Spoilers thread, so...as always...THERE WILL BE SPOILERS!
So far, the only "Spoilery" thing rn are the names of the dungeon/raid.
Dungeon: Seat of the Triumvirate
Raid: Antorus, the Burning Throne.