Blizzard Planning Another Unannounced Title

One glance at Blizzard's US jobs page, and we see familiar faces: World of Warcraft, Diablo III, Starcraft II, and a "Next-Gen MMO" which is most likely Titan. So what is this "Software Engineer, Tools" entry beneath "Unannounced Game Title"?

Blizzard isn't known for dabbling outside of Diablo, Warcraft, and Starcraft, so with Titan already a surprise on that front, I suspect that this might be a sequel... like World of Warcraft II.

[Source]
[Image Credit: Eurogamer]