Why is Georgia potentially competitive in the near future, but not South Carolina?
It's just demographically closer to being a swing state than South Carolina. I'd say the order of coastal Southern states goes (from bluest to reddest) Virginia, Florida, North Carolina, Georgia, South Carolina, Mississippi, Louisiana, Alabama.
True, Georgia is much more diverse. Still, South Carolina gets far more Northern transplants than Alabama, Mississippi, or Louisiana. Politically, South Carolina seems to be more like Georgia than those three Gulf Coast states.
A lot of those transplants are retirees, who mostly vote R. I think Nate Silver has a good post on the subject.
