Given the timing (I still expect a Sept 23rd/30th release), I think they could hype up and announce T18 at Blizzcon, the middle raid tier for WoD. Imagine the reaction if it was another troll raid =p j/k
The middle of an expansion does present an opportunity to do something totally different but we have a lot of established Warlords to kill off. Still doesn't mean we won't get multiple raid instances again. I'm thinking one of those will be an arakkoa raid.