My notion is pretty flawed, as you note above, and it wouldn't be any 10 minute HSR ride. It takes 10 minutes to ride the Plane Train from one end of the current airport to the other. I was figuring 100 miles SE of Atlanta. Cancellations would be a major issue, missed flights, etc. The original proposal would have been about 60 miles north of Atlanta near Dawsonville. I'm not seeing anything that would really work. The hub and spoke model means airports in places like Augusta and Columbus would stay minor.
They spent $1.4 billion on the International Terminal with only 12 gates, it's astounding really. And now it's jammed at the end of the day, not in the AM apparently.