During Gamescom this week, Game Informer spoke with World of Warcraft game director Tom Chilton and asked him if Blizzard ever considered making World of Warcraft 2. "Definitely," he said. "It's something we have talked about. It's something we have talked about for ten years."
In the article is more information what else did Tom Chilton said and the truth is that he acknowledge that many problems and facts would have to be taken into consideration. So do not expect WoW 2 soon :-).