Georgia has much better things to do with its resources that fund billions of dollars (and thats what it will cost) to build an white elephant.
I don't think anyone is talking about a project of that grandiose scale. I suspect any sort of "second commercial Atlanta-area airport" project would be akin to the privately-developed terminal at PAE or a low-cost project like the PGD terminal or the new LGB terminal which came in under $50 million even in the high-cost L.A. area. Maybe a carrier like G4 or NK would be willing to fund the project out of its own pocket.
ATL is better located than any possible alternate site.
It's not well-located for the northern suburbs especially in light of Atlanta's notorious traffic.
Anyone who has endured the TSA nightmare in Atlanta knows full well that the model is not working well there and shows why the city needs a new airport.
A second airport isn't necessarily the solution to that particular problem. Expanding the security checkpoints, increasing TSA staffing to fully utilize the existing space, or improving TSA's efficiency in screening passengers (LOL) would be more appropriate. A second commercial airport in the region would really be more about offering less hassle in getting to the airport for some of the population.
The 2nd airport isn't going to be located in a better location. It is going to be located in the hinterlands, far far away from the important employment centers. This evaluation has already been done. The possible sites are either too far out, or too close and not politically viable (Dobbins, PDK, Charlie Brown).
Look, a private developer could come in a turn some far off GA field into a commercial service airport, but it sin't going to have political support. At best, it will be a small G4-type operation. But, G4 has already been down this road and has chosen to step back. Whatever might be potentially developed will never become a real alternative to ATL.
Cities with multi-airport systems tend to have an old, small close-in airport and a newer, larger, more remote airport. That would be flipped on its end in Atlanta. The larger, closer-in airport will always be ATL. The secondary airport will be small and poorly-located. Atlanta will not look like Houston, Chicago or Dallas in our lifetimes for all these reasons AND the fact that there is NO political support fo this idea. That matters here. A lot.