Well it's possible but not probable. Usually the biggest games ever has 20%-25% attach rates. So for that 16 million to come true on 360 we are looking at least 64 million units sold and upwards of 80 million systems. PS3 on the other hand in the 40-50 million range. Now that's a lot of systems for each to sell with the PS3 possibility being a lot higher.
As I said it's possible but these games are going to have to sell like Nintendo games for the next year or 2 and well the first Modern Warfare didn't do that. The more frontloaded Modern Warfare 2 seems even more of a longshot. I'd say more around 20-23 million seems possible but hey it could do it. Just have to see how the game competes with the likes of the next Call of Duty games, Halo Reach, etc.