According to an article in the LA Times, Activision - Blizzard has put a third team to work on the Call of Duty series. No word about which studio and what they're exactly doing, unfortunately.
By now we've learnt that CEO Bobby Kotick is dreaming of a MMO part in the series, while CFO Tom Tippl on the other hand wants to earn more money with payable online supplements.

Next to Infinity Ward and Treyarch, other devs like n-Space (dev of the portable versions) and Certain Affinity (helped with designing the multiplayer maps for Treyarch's CoD: World at War) have previously worked on the series, but also other experienced FPS devs like Raven Soft and High Moon Studios (Darkwatch) are part of Activision-Blizzard so it seems there's plenty of choice to have someone work on yet another Call of Duty title.

Another possibility is of course that Activision has assigned their newest studio, Sledgehammer Games. The former Dead Space developers could give the franchise a futuristic twist.

Of course, the L.A. Times can also be completely wrong on the entire matter...

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