The next expansion of World of Warcraft could be "Eye of Azshara" after Blizzard, the producers filed a trademark for it according games news sites such as Gamespot. For those who are not in the know, Azshara is both a zone in Kalimdor to the north of Durotar and one of the early playing zones for Goblin.
However it more likely to refer to the Night Elf Queen who ruled Azeroth thousands of years ago when the Burning Legion first attacked. Azshara caused sundering which split the one continent into two. Azshara was turned into a Naga and was never seen of since. The name implies she could be making a return. With Blizzcon, the annual get together of Warcraft fans could reveal more on this. Azshara at the moment can be seen in the dungeon Well of Eternity.
If not an expansion for World of Warcraft, maybe for one of its other games such as Hearthstone.