Alright, This may be already used in game somewhere. I don't know..only BC raid I've been in is Kara and only got to Moroes. However, here goes:
I was looking around in the expansion.mpq archive and found this model under the directory path "CREATURE\MOUNTEDDEATHKNIGHT\UnMountedDeathKnight.m2"
Could this be the model for the new hero class?!