If...and I mean.. IF Queen Azshara does not make an appearence in this expansion, she will most likely be in the last, and I have a feeling our next two races have already been introduced.
Well one in this upcoming expansion the Jinyu for the alliance and Renegade/Rebelious Naga for the Horde.
This is all illrelevent if Queen Azshara makes her raid boss debut in this expansion though.