That's all fine and dandy, but it wouldn't be the first time Blizzard said one thing and did another.Metzen already said last blizzcon that alleria and turalyn will be returning after mop . Mostly likely were heading back to outland /burning legion. https://www.youtube.com/watch?v=2JhX-dfCLyA after the 9:00 mark metzen says it.
'After MoP' could be the expansion directly after or any number of expansions later. Blizzard is intentionally vague so you and I can't get pissed and rage on the forums when they change their minds on what to do.
All this aside, MoP was a stand alone expansion, really having nothing to do with the rest of the game, the lore being so fleshed out in the short time they had to develop it. It also showed they could do an expansion that departs from the status quo within their game development, if need be. There is no end to Wow, if they don't want to end it, even if the lore dries up.
They can just invent more.