Here is what I have concluded for 2 and possibly 4 xpacs from now:
Alliance:
next race - Broken. They are already part of the Alliance.
alternative - Arokkoa. Hmmmm-mmm??
next next race - Furblog. Too soon after furry Worgens. But obvious choice due to friendship with Night Elves.
Horde:
next race - Ogres. They are already part of the Horde.
alternative - Satyr. Bad ass, 'nuff said.
next next race - Gnoll. Too soon after little Goblins. But Hogger. Hogger.