Not a huge amount announced at Blizzcon this year. For WoW, we got the trailer for Patch 9.1: Chains of Domination.
So it looks like Anduin is being controlled by the Jailer into a quasi-Death Knight. The Covenants will be going on the offensive, attacking the Maw. The new raid will be attacking the Sanctum of Domination in Torghast. There's also a new long Mythic dungeon like Karazhan or Mechagon.
Nothing unexpected, but it all looks pretty decent.
Regarding the story, and Anduin being mind-controlled, I was amused to recall the start of Pandaria. In the Jade Forest questline, Anduin mind-controls Sully into letting him escape. Maybe a touch of karma there.