All the disease and sickness cannot just be excised like a tumor, it's too advanced, too widespread throughout the whole body, too deep in it's bones.
This isn't Stage 4 cancer, we've gone beyond that.
We're fuckin' Deadpool at this point: We ARE cancer.
Balkanization seems pretty unlikely. I could see some sort of ideological break up, where you've got two or more different states that each claim to be the legitimate successor to the US that have different ideologies, but that's historically been a pretty unstable situation without some form of massive military investment from outside powers.