Ok, let me put up something regarding people wanting Pandaren as a playable race. It's never gonna happen. The WoW guys are real punching bags when it comes to anything regarding the Chinese. They had to cover up the bones on undead and abomination models, and they had to remove all the skeletons (what sense does that make on the Lich King's front door?), so if you're hoping that the Pandaren, a race based heavily around pandas, a highly endangered species and something that China is dead-set on protecting, are involved, you're dead wrong. They would not let the expansion out there because to them, showing even virtual harming of pandas breaks the endangered species laws they have adn they will immediately break out the murder sticks. I don't think they'd be diametrically opposed to seeing the pandaren in the expansion, but in a way that you can't hurt them. Which means there's a possibility of Pandaria becoming a Sanctuary, but the possibilty of Pandaren being playable is somewhere between zero and none.
Goblins might be an acceptable 'neutral' race, though. They have a male and female model, they have a well-established capital (Undermine), they have their own language (which I do not know what it is called, I assume Goblin), and they have a number of possibilities of racial leaders, the goblin Trade Princes (Ratso Steamwheedle leading the Steamwheedle Cartel, Mogul Razdunk leads the Venture Co., et cetera). Goblins also have a number of open ideas for racials, like a passive bonus to Alchemy (Mix Master) and a resistance to Fire damage (Fireproof). They would however need their own attack/cast/walk/run/etc. animations (they all currently use the animations of male dwarves, with the exception of the males' dance) and the playables would need their own dialogue lines. There's also the question of what classes they would have access to. Warrior, Mage, Warlock and Rogue are obvious choices, but I think they need one or two more. The last thing against them is what would they use for mounts? Would they follow the gnomes' idea and use a mechanized version of a bunch of animals (mechano-horse, mechano-wolf, mechano-tiger and mechano-raptor, maybe?) or would they just use one-seater go-karts or something? Actually, that go-kart idea sounds pretty plausable.
Another possibility of a neutral race is ogres. They have a well-established set of classes to choose from (Warrior, Mage, Priest, Warlock, Shaman, Hunter), they have their own established casting, attacking, dancing and other animations, and they are completely impartial to who they work with. However, what they have seems to be evened out by what they don't have, in much the same way the goblins do. They don't have an established leader or capital, they don't have a real language (most just speak broken common or broken orcish) and they don't have a female model. One could argue that they reproduce asexually and just give them one- or two-headed models, which actually might make a decent substitute. And again, they don't have their own lines or mounts.
EDIT: And I know there are a lot of WoW haters out there, but even so, this is a topic dedicated to fan speculation of what to expect next. If you hate WoW that much, make a thread about it and go there to hate. Or at least give a reason why you hate it to make your argument more valid.