I don't see how NC is "doable" for Obama this year. He carried it by 14,000 votes (0.32%) in 2008 and it just voted against same-sex marriage 60 to 40.
That comes down again to that question... is Obama's personal support enough to turn them off voting for him regardless of anything else?
I think people need to be REALLY careful trying to marry (NPI) these two votes together too much.
Obama can and will certainly win people who don't support gay marriage, his issue will be turnout and what his statement has cost him.