It is actually an interesting concept of human philosophy. I for one, have had thoughts about this, and I actually might come 2-3 more years. My thoughts on the topic at hand is that in that time, nobody will use MLC, UMP, OMADC Noot Tubes. I imagine it as such, because I play CoD4/WaW on PC, and I barely see TB flying around, only lots of grenades with 50 players per server.
I've also heard that CoD4 on PS3 is much better in terms of game play because all the "cheap" things have disappeared, or at least the players left.
So with that said and done, I believe in 2-3 years, MW2 is be playable (hopefully) on the PC/PS3/MAYBE 360 (Seeing as 360 is known in my opinion, as having the most annoying play styles).