Moving to ATL is a good idea in theory. Problem is Sun night is the big primetime NFL game, and NBC does a lot of prep for it onsite. Takes about 3 or 4 days typically to setup cameras/equipment plus testing. If you move Bama/UGA to Sat night, they’d have to allow ABC to move in/out their production setup the day before, which would narrow NBC’s setup time to about 18 hours. I don’t think they would allow that.
My guess is IF they postpone the game, they move it to Mon night. Either keep it in Tuscaloosa (weather permitting of course), or ATL. That last one would still be a challenge production wise, but I think ABC could make it work in a pinch. That is only a guess, and just going by what's been done before.