It's difficult to speculate. As has been pointed out earlier in the thread: CoD is a shooter, a genre that has always been strong since it's full conception.
Either there'll suddenly be a spur of consumer wisdom (which is unlikely given humans are the consumers) and people will see it's the same thing over and over and thus stop buying, it will live on forever like a gaming Bruce Forsyth, Activison will actually start giving a crap about producing decent games (Unlikely unless Kotick dies (But one can pray)) or a better, bigger shooter will hit screens.
I'd go with the lattermost. Give it a few years.