If we are fortunate enough to make it, I think tix will be easily attainable. Clemson representing the Atlantic could make ticket getting a little harder due to their relative location, but there is a lot of football between now and then. I would actually be more concerned about getting a hotel room within walking distance than finding good, affordable seats.
edit: Don't forget the game is at night in December. Weather, Xmas parties and Xmas $$ constraints usually keep the average fan away from the ACCCG. The reason the SEC sells out is because:
1) Its usually Top 10 teams.
2) Its inside.
3) Less than 6 hour drive for both teams.
4) Atlanta has an abundance of affordable hotels within 20 minute drive of the dome.
5) Lots to do in host city (ATL) regardless of weather.
If the ACCCG had these 5 things it would sell out every year also.