I don't buy the notion that a 'soft-AC' station (targeted at an older audience) will fail out of the box. It is quite possible that it would do well here - give it a try and tweak it.
Atlanta is such a young market, and it waaaaay inder-indexes on percentages of the population in 55-64 and 65+. That makes it hard to get the boxcar numbers needed to sell a format most advertisers are not really attracted to.
Again, I'll repeat the story of WDUV in Tampa with its soft AC format. For a decade and a half, it was a solid, far-away #1. But most of the listeners were 65+. So they averaged about 15th in market billings, dead last for a relatively full FM signal.
They freshened up the format after the Miami experience of sister WFEZ and lost a lot of the geezers, but gained 35-54. They are now in the top 10 stations in sales, and growing.