I'm also a believer with 2 more expansions, ending in level 100. The next big project will be titan. and that will be the main focus for blizzard.
I do believe WoW will continue to have expansions... instead of a level increase, it'll be an item level progression based expansion, ending with all items in slot being legendary, it will also introduce probably a couple of novelty races, and a class. Along with some fun raids.
From there I think wow will just release digital downloads for new races, and maybe a fun class or fourth spec for an existing class here or there.