While reading around I found this article Link. My friends can testify that I predicted the races of The Burning Crusade well before the expansion came out. I don't see any races coming out in the lich king but the walruses are an interesting race. Not too sure about that.
Neutral Candidates include:
Goblins, Ethereals, Tuskkarr
Other Candidates include:
Naga, Dryads (Not Likely), Centaur (Not Likely), High Elves, Anubisath (or whatever) humanoids, etc.
I, for one, would love to see a 'neutral' faction available for play. I want to roll an Ethereal mage ASAP. One that can visit ether horde towns or alliance towns without any penalties. Good luck dreaming eh?