Production director Patrick Dawson to IGN:
this time there won't be an option to keep characters in The Burning Crusade expansion. Everyone who's already in Burning Crusade must move on to Wrath of the Lich King.
Fortunately, Dawson says that not many people currently in Burning Crusade want to stick around in that expansion anyway.
"People want to experience certain eras of WoW in the progression style that is meaningful, and Burning Crusade has done that," he says. "I think there are opportunities in the future to look at different seasonal content we can provide to people who are looking [to] revisit BC or… revisit Classic again. It's something we're always keeping an eye on to see what we could do."