Infinity Ward is done with Activision. It was widely covered and Activision's jack-booted approach to clearing out the studio ended up doing more harm to their public image than just about anything else they did this year.
Either way, Activision believes it's the IP, not the development studio that makes the franchise successful. And while I feel IW is a better developer than Treyarch, 9m copies sold in the opening weeks for Black Ops say most people don't care.