StarCraft II: Legacy of the Void producer Tim Morten says that Blizzard may revisit the Warcraft franchise as a real-time strategy game once StarCraft II is complete. In case it wasn't already obvious, the StarCraft II trilogy is set to conclude with the release of Legacy of the Void.
The producer also said that the studio may be looking at developing StarCraft III with all-new characters.
"This isn’t the end of StarCraft, but it’s the end of this story for these characters," he said at Gamescom 2015 in an interview with IGN. "We don’t have any specific plans, but I’ll say that the universe has so much potential for more stories, clearly other stories could be told.
"It’s very rewarding for us to hear that there’s demand out there for more RTS content in the Warcraft universe so once we’re done with Void I think we’ll get together as a team and talk about what would inspire us to work on next. There’s no question, though, that we’ll consider Warcraft, StarCraft, or even new ideas. Anything is possible."
Given that the studio is also working on new franchises like Overwatch, there's even a chance that the studio may decide to work on a new franchise entirely for its next RTS instead of going back to either StarCraft or Warcraft.