Blizzard painted themselves into a corner?

Blizzard has an amazing track record, everyone knows that. They are also known for perfecting other people's work instead of doing something totally new. What's more, a large core of their founding brain pool left during the creation of World of Warcraft, meaning the company has moved more into the hands of their corporate slave-drivers, Vivendi. All signs point to a sequel as their next game, but what could it possibly be?

They just made World of Warcraft and Warcraft 3 before that. This has tapped the entire company, I highly doubt we're gonna see anything other than a WoW expansion for a long time. Diablo 2 is looking very dated, but we won't be seeing a sequel to that soon, because WoW is basically Diablo Online, only set in the Warcraft universe. It wouldn't make sense to make the same kind of game twice. Then there is Starcraft. We have SC:Ghost coming soon, that should be amazing, but it's not fully a Blizzard game. How about Starcraft 2? Another RTS, though, so soon after Warcraft 3? Let's hope so. Or even better, a completely new work, a FPS, or an adventure game, or something else. A return to their vikings game. I don't know.