Have we finally reached zombie saturation?

Maybe 10-15 years ago, once in a blue moon, we'd receive a game that might feature zombies. Now, it seems like every single game that comes out has to include some sort of a zombie mode. It's cool to see something different happening, but at the same time, even though it's only been two or three years since Left 4 Dead reminded people how fun it is to kill zombies with friends, is it possible that there's too much of a good thing happening?

The big reason why I feel like zombies caught on is because for once, instead of worrying about shooting brown people or Nazis in the face in some fictional take on a war, you were teaming up with friends to take down hordes of a new type of enemy that only seems to pose a threat in large hoards. This is wonderful and all, but...I feel like it started getting out of hand with Saints Row 2, and now that Crackdown 2 features tons of them to fight instead of fictional games, it's making me scratch my head in confusion.

Is this really necessary? Aren't there other ways to do co-op? While Left 4 Dead, L4D2, Killing Floor, and Nazi Zombies are all good fun, what happened to the days when it was fine to just walk down a street, fighting thugs in Streets of Rage, or the 4 player fun of Four Swords where you were on a quest? I'm not saying that zombies need to be out of games completely, but if you're making a game and want to let people work together, there's still some other things that you could do that are almost untapped.

GTA4 had an awesome thing going with its multiplayer exclusive co-op missions and its tight knit team v team v team v team modes. New Super Mario Bros take on the traditional Mario formula, then throwing 3 other players into the mix easily helped it on to many peoples top 10 games of 2009. At the same time, I wouldn't be the least bit surprised to see a game like MAG add in some bizarre 256 player zombie mode in the future, provided zombies keep selling like hotcakes (do those things actually sell still?). Anyway, I think I've rambled as long as I can about this, so let's just remind ourselves to keep a tally of how many last-minute zombie modes make it into 2010.