okay this is pretty interesting.
read a 2008 article which said this:
Quote:
So far only two classes have been revealed for Diablo III, the Barbarian, which returns from Diablo II, and the Witch Doctor, a brand new class. Blizzard has already confirmed that no other classes from Diablo or Diablo II will make it into the third game.
Wilson told VideoGamer that the next class it announces will be “quite similar” to a previous class and promised that Blizzard will consider bringing back old classes in future expansions to the game.
So you can rule out ranger and paladin. until the expansion at least.