As I finished watching the multiplayer trailer for the thousandth time, I noticed at the end where the 2 comes in, just to the right was a 3. Given that the previous number was a 1 I assumed that the next number was a 3. This is by no means officially confirmed, I am just stating an observation. Infinity Ward is obviously going to milk this franchise dry. But given that the MW 2 looks different from 1, I will at least give them credit for not just putting a new skin over an old game.

Here is a Picture