back when the first nazi zombie map (nacht der untoten) was out i remember someone telling me that treyarch was making "4" map packs. So far its a possibility since we do have 3. You never know... If they do release it theres still a chance we might be lucky enough to receive another if the backstory doesnt finish. Modern Warfare 2 is not Treyarch so yeah theres still a slight chance theres more maps to come even after the release of MW2...