I never buy CoD maps. They're overpriced and the next game is always rushed out by next year. I'll just pay $60 for the next game instead of $50 for some maps.
IW will again bring something new. MW2 introduced spec ops. MW3 introduced Survival (on all Mp Maps). And other stuff like dropzone, infected...
Wonder what mw4 will have in store (mw4 isnt officially confirmed, but some of the voice actors said its going to be mw4). Maybe IW (as they are now the nice COD company) will bring us that map editor.
Wonder if TF will make it into MW? Also some more AI controlled robots would be nice, like the AGR.