Someone looting through the game files of Modern Warfare 3 was able to find a few .iwi files that referred to some maps in previous Call of Duty games. The .iwi file extension is an image type that’s used by Call of Duty’s engine, and is a converted DDS image. Image from MP1st after the jump.
As you can see from the highlighted parts on the image I pinched from them, there are five image files that are the loading screens for five maps from previous entries. It is normal for dummy data to be leftover if one game is built directly on top of another engine which is a common practice, but it could also be hinting to the fact they may be planning (or had planned) to release these maps in the future.
A few maps have already been remastered for MW2 and 3, so whenever this is dummy data or a small hint put in by someone, intentionally or otherwise, remains to be seen. Of course, I’m leaning heavily towards it being dummy data because of the fact that a message that appears in MW3 explicitly says MW2, which has since become quite a joke on the internet itself.
Regardless, keep your expectations low, it would be nice to have some really good maps remastered and released for a later console, since the maps in multiplayer games are often one of the most iconic things about them.