Surprise! Jay Wilson may have slipped somehow that a Diablo 3 expansion might follow after the release of Diablo 3, and the Necromancer class might return in the expansion. It is not set in stone, but it is a fair hope that the Necromancer or previous classes may be brought back. Read the full article at MTV Multiplayer
... for those who are really passionate about the Necromancer, there’s still hope to see the class in a “Diablo III” expansion. In fact, Wilson thought that expansions might be a great place to bring back any of the old classes not included, particularly since the team itself had passionate debates on the topic — almost as much as the game’s art direction.