The problem with a "Vs. America" game is the same thing that's wrong with all games that glorify American combat. Sure, something against America would add a little variety. But they still do the same thing of making one country/faction/people "the bad guys".
As to the people who say that America doesn't make up the entirety of the gaming market. To this, I will say that America and its allies comprise most of the gaming market. The same reason you won't see a game outwardly villainizing American forces is the same reason you won't see a game that mass villainizes England, France, post WWII Japan and Germany, Canada (although who could hate Canada?), etc.
Has America made mistakes? Of course. But, when push comes to shove, America has the back of the majority of countries that make up the gaming market as we know it. That's why it's hard to paint them as the villain without projecting into the future or proposing an alternative history.
On another note, I seen about the Taliban vs. America. Ok. How about playing the IRA vs. English forces? Does that sit well? How about Chinese Guerrilla forces fighting against Japanese Imperialist invaders? Maybe the Vietnamese driving the French out of occupation?
I'm not saying that any of you from these countries have any issues with portraying these conflicts in video games. Most people who game (by and large) are probably not all that conservative (being as though we support a medium that largely comes under fire from conservatives). I know I could give a fair look at playing the proposed "Vs. America" game.
But, when you're villainizing a country, it's not just the gamers of that country who are going to have the say in things. I'm not sure how many gamers live in Cuba, but Cuba seems pretty upset over the assassination mission in COD: BO.
What I propose is to start creating fake game worlds with their own politics and stories. Not only does this drive away from stereotypes regarding nationality, but allows for the exploration of stories and technology that are apart from what we already know. These may offer allegories and symbolize some modern issues and world players, but by keeping it out of the realm of true reality, you allow all players to experience the game without their "world view" glasses on.