Kotaku writes Activision has reportedly created a third Call of Duty development team. The site speculates this third team may be focused on the creation of a MMO take on the series:
One possibility could give current Call of Duty developers Treyarch and Infinity Ward more time to produce entries in the core series, offering them a three year development cycle instead of the two year turnaround time in place now. Another is semi-annual releases, which may be pushing it.
Or, this third team could be focused on a different Call of Duty model. Activision CEO Bobby Kotick has publicly expressed this thoughts on a massively-multiplayer online take on the series. Activision CFO Tom Tippl has also teased "additional online monetization models" for the Call of Duty brand.