(Just be clear, this is my own idea, SO BACK OFF!!! I NEVER CLAIMED THIS WAS FACT!!!)
At the end of the first game, Chris says that he Reds will probably just come back with reinforcements and reattempt to take and hold the city. What's wrong with that? What I think would be cool though is if they made the game online and everyone plays as their own custom Freedom Fighters in Chris' army, kinda like what they did in Syphon Filter: The Omega Strain, and you fight off the re-invasion/retaliation forces.
I know it'll never happen, but what do you think, assuming any of you actually read this?