They also protect WAPA, the only higher power non-directional station on 680 in the Eastern USA.
So no signal to the southeast, either.
That would eliminate Canton, then. The WCNN night pattern seems to aim mostly southwestward today, and that would explain why. But WDUN Gainesville would be an option if they could thread the needle and send all the power southwestward, basically along and either side of the I-85 corridor. That would pick up Forsyth and Gwinnett and Cobb countie$$$. Cherokee would be a wash or maybe a little improvement.
The WDUN night pattern looks like this: https://radio-locator.com/cgi-bin/pat?call=WDUN&service=AM&h=N
Just rotate it 90 degrees clockwise and up the power from 2500W to 10kW, and bigger nulls north of the site.
One concern from looking at both their day and night patterns is that they may be topographically compromised going towards the metro area--seems to be an ongoing concern with stations to the northeast of town, trying to get over Peachtree and the other ridges, which is evident with WXKT and WDUN-FM and WBCX as well.
They could continue to do days from their plant off Spalding in Ptree Corners, using two towers, and nights from the WDUN site in Gainesville. Covering Brookhaven (fka North Atlanta) shouldn't be an issue. And they could tear down 6 of their 8 towers and liquidate some of that real estate in a pricey part of town--although a lot of it is in a floodplain.
Of course, the usual questions remain--what is the ROI on improving an AM facility these days? Can they pull off the required night pattern? What would be the loss of using antennas tuned to 550kHz and not 680kHz?