Like The Bad Guy?

I like the fact that you play as different characters from different places in the COD franchise but what if you could play as sheppard? of course he is the bad guy but, i think that it would be kinda cool to have the choice to play as sheppard or markov and follow their life and choices, and it would be badass to let off a nuke like in COD4! even better you could play BOTH in the new MW3, the good and the bad and get more gameplay out of it, you know get 2 different endings out of it even if it took 2 discs to do it, hey i'm game...