User blog comment:KATANAGOD/Call of Duty: Black Ops II In-Depth Preview/@comment-189.85.173.140-20120502150312/@comment-3575339-20120502175013

My guess is there will not be a new COD Engine until a new console comes out. Activision has adopted the "one cod per year" stance, and that only gives a game developer roughly a year to design and develop a game, there won't be enough time to develop and revamp a whole new engine, jsut update regularly.