The class "Assassin" is already in the dats, which sounds like a Theif/Ninja hybrid to me. Fencer is included as well.

Judging by Yoshi-P's letters, it seems he prefers to fix/adjust current systems before implimenting new content (which I agree with), so it might be a while before the extra classes are actually unlocked...

If it makes you feel any better, I can guarantee I will have as hard a time waiting for them to unlock Mystic as most of you will have waiting for Ninja...