NC's rapid shift left in 2008 has certainly stalled for the time being, but that does not mean it is unwinnable. NC's biggest issue is it lacks a main urban center like Atlanta where Democrats can run up massive vote margins to offset the rural areas of the state. Until Charlotte/Raleigh can get to the margins you see in Atlanta, NC is going to be hard to win for Democrats.
That's not even the problem.
The problem is that, in NC, Democrats still have room to collapse in the rural areas, but not in GA or VA.
You see a lot of rural areas in VA and GA where Democrats get <20% of the vote and you don't see that in NC.
Basically, the gains Democrats get in the urban area is cancelled by rural swinging Republican.