I'm surprised this hasn't been reported on yet but apparently Blistered Thumbs, a website for gaming, got information that points to Blizzard's upcoming game (simply titled "Project Titan" for now). Here's a direct quote from the site:

"Blistered Thumbs has obtained exclusive information that lends credence to Blizzard’s upcoming Project Titan being a shooter. A reliable source tied to the project has shared with BT that a large portion of the development staff from Bethesda’s Brink have been hired to work on the yet unrevealed game. The source did not say specifically what genre the game would be, but heavily implied that we should be looking at the track record of the Brink team, Splash Damage.

It’s worth noting that Splash Damage has worked exclusively on FPS games in the past, which include iterations in the Doom, Wolfenstein, and Quake series. I’m sure many are hoping that this might be the revival of the ill-fated Starcraft Ghost, but Blizzard has gone on record to say that this will be a brand new IP for the company. While not a Blizzard game, this would add fuel to the fire of an alleged Halo MMO." Link: http://www.blisteredthumbs.net/2012/04/project-titan-likely-a-shooter/

I'm not really putting much stock into this rumor because I don't see why Blizzard would think a shooter would even be a good idea... There is already so many of them out there and I don't really see how this could be the next big thing after WoW. But hey, stranger things have happened.