I do wonder why you're even asking this here given the amount of unbridled MW2 hate that exists here. It's sort of like asking a mouse if it would like to be thrown into a cage full of cats.
Would I pay? No, absolutely not. But then again, I also barely play anything other than MMOs online.
Ask an actual dedicated MW2 player if they would, though, and you'd likely get a different answer especially if the price was right and said subscription included things like free maps, weapons, gear, etc. Heck, serious MW2 players already don't mind paying $15 every few months for a couple of new maps and a couple of refurbished ones.