Bashiok replied today to a fan impatient for more info on the fifth character class. I’ve inserted a visual aid to help you envision what I think their original design concepts for the 5th character were.
The fifth class was something that was decided early on, but after continuing to work on the game and the other classes it just wasn’t up to standards any longer. So it’s back on the drawing board.
We only have one class left to reveal, it’s sort of a major card we can still hold close to the vest. While development doesn’t depend on our plans to reveal it, we definitely aren’t going to tell everyone what it is just because we know what it’s going to be.