If I recall, Black turnout in Georgia actually fell in 2012- probably due to voter ID. However, the demographic changes in Georgia aren't the kind that will be canceled out by any potentially decreased turnout- they'll make up for lowered turnout an then some.
Precisely. These Republicans hoping to blunt the dying off of their whites with minorities non-voting (either voluntarily or through coercion) are missing the point - the demographic changes swamp minor differences in turnout over time.
I actually think the trends in Georgia are more likely to put the state in the D-column long term than those in NC and VA. That's simply because in the latter 2, the shift is more dependent on moderate white suburbanites.
You may have a point about NC, but VA is pretty much gone in the longer term for the GOP.