The trademark is "Overwatch", a term usually used to denote small, supporting military units. Blizzard hired Left 4 Dead developer Michael Booth last year, and it seems like he is directing a small project, with a similar team size to Hearthstone, that isn't Titan. There have been various job listings for positions with this new project, some of which talk about multiplayer experiences and maps. Now this might all be nonsense, but perhaps it points to a new military-styled game coming out of Irvine.
There has long been speculation that Blizzard's next franchise would be a shooter, but with Titan ostensibly on the shelf for now, could this new small team production be that game? We're understandably cautious in our presentation of this information, but it's certainly interesting.