Maybe a third company could make a small non-cannon Modern Warfare RPG. At the start you can pick waht group to join, Army Rangers, Marine Recon, Shadow Company, Task Force 141. Then it all depends on decisions on what you do.
Example: If you join Army Rangers, Foley will ask for advice on weather or not to offer his squad for invasion of Moscow. If you say you should go, you'll go to Moscow, if you don't you'll stay and fight in America. Maybe there's a part when you're on a plane and it gets hit in Moscow and you must choose to lift up Dunn or Foley, as the the other will fall and die. If you stay in America you will stay in America and guard the Pentagon from an expected Soap or Price inavasion to kill Shadow Company's new leader, General Marshall.
Of course it would take some time to make, but it would make single player a lot more. I loved Fallout 3, how you could choose people to die and who to kill and let live. I mean really it would take forever, and you'd get all this new stuff. I had to beat the game three times (good karma, nuetral karma, bad karma) and there was a lot of stuff for each side, and thats why people just ate it up.