From the interview:
Some people say that the decision to release StarCraft II as a trilogy is a sign of Activision flexing its muscle over Blizzard—to “milk” the StarCraft franchise. Is the trilogy format related at all to the Activision merger?
No, absolutely not. [Activision] does not play a factor at all. One of the things that [StarCraft II lead producer] Chris Sigaty was saying in interviews this weekend is that we had always planned to do two expansion packs for StarCraft II. This structure just reshuffles how we were going to do things.
Just to give you some context, typically with Blizzard RTSes, we release a single-player campaign that gives players just a taste of each race. The original StarCraft had 10 missions each or so for Terrans and Protoss. When we released the Brood Wars expansion pack, there was another eight or so missions for each of the missions.
All we’re really doing is reshuffling how players are going to experience the single-player content. In StarCraft II, we’re going to have a campaign that focuses strictly on the Terran. It’ll be 26-30 missions long, and you’ll play as Jim Rainer. When we release first expansion set, that’s going to focus on Zerg. So that’s going to be another 26-30 missions strictly focusing on Zerg. When we go to the final expansion pack, it will be the Protoss experience, probably another 26-30 missions.
I think the readers aren’t understanding that there’s a full, gi-normous single-player campaign experience in each of these three products. Instead of getting all three race experiences at once, to make it a more epic experience, we’re focusing on one faction per entry for the single-player.
So there we are. More through the link.