When asked by GameSpot if the Warcraft universe was all that's left for the company to mine, chief operating officer Paul Sams said, "No. Absolutely not. We have multiple games in development, currently, they are just not announced...to the outside world--and the reality of it is--we are laser focused on what is the thing right then, but there's a ton of additional focus being put toward these other [games] that are in development."
Reflecting on the existing franchises, Sams emphasized, "World of Warcraft and the Warcraft franchise is not the last and the only franchise we are going to operate within. We have two other very, very key franchises to our company's history and to our company's future success. The Diablo and Starcraft franchises are of the utmost importance to us as well. I wouldn't be surprised to see a new franchise from us at some time in the future; there's certainly a desire to do so."
Here's hoping for SC2!