The voice actor for the character Ghost in Modern Warfare 2 let a little information slip when talking about the future of the character. “…in this game I’m now voicing a guy called Ghost, who now just got a spin-off comic of his own and they’re talking about another little game to go with it”
It’s kind of hard to say how big a “little game” is. Maybe it could be DLC missions for Modern Warfare 2, but your guess is as good as mine.
(Source: That VideoGame Blog)