AusGamers recently interviewed StarCraft 2: Heart of the Swarm producer, Kaeo Milko, who revealed that with SC2, the team approached the game differently, separating completely the single-player and multiplayer components.
"We kind of took a new approach to RTS games for Wings of Liberty and we’re carrying that into Heart of the Swarm as well," Kaeo told AusGamers. "Because historically, the multiplayer units had been featured prominently in the campaign and we used campaign as a training ground for multiplayer. But for Wings of Liberty and for Heart of the Swarm, we’ve given ourselves the liberty to disconnect that a bit more, which has been kind of cool actually..."
They also broach pro-gamers working with the team on balance issues, the sequel's narrative future and much, much more.