We're probably years away from the Atlanta Falcons playing football in a new NFL stadium, and not just because it takes time to make that happen.
The most major hurdle for the Falcons is that the other teams who play in the Georgia Dome--like the college teams in the Chick-Fil-A , among others--won't play in an outdoor stadium. Arthur Blank and the team would like an outdoor stadium to play in, so that's not going to be easy to do.
There are essentially two potential solutions to the issue, besides building a new indoor stadium. I imagine Blank would sooner buy Lowe's than build another Georgia Dome, so that's probably a moot point.
The first solution is building a second open-air stadium close to the Dome, so teams can share the fields. That would give Atlanta two options and give the Falcons their open-air field, so that would be workable. The big question then becomes where, exactly, you slot that second field in a crowded downtown. Chances are good you don't, and build the new field a bit further away.
The second option is to build a field with a retractable roof. You can then keep the elements out when necessary and keep it closed for those games that required it, as well, but still have open air and sunshine otherwise. This option could likely be built on the existing footprint of the Georgia Dome.
Ultimately, I imagine the retractable roof will win the day, but that's more of a guess based on the city's ability to support multiple stadiums than anything else. What do you think?