Personally, I think it'll keep Call of Duty alive for just one more measly year.
Next year Treyarch will have a bunch of "great" ideas to make Call of Duty better.
Modern Warfare 3 will be "ok." The next Treyarch game will be so garbage that you'll wanna go to 3arch HQ with your Xbox 360 as a weapon. After you throw your Xbox at them, you'll use the useless game disc for their CoD game as ninja stars.
Honestly, the FPS game i'm hopeful of is the next Rainbox Six game. RainboxSixPatriot in 2012? I hope.