They should probably move the Nashville site to a larger city. Maybe Atlanta. Atlanta could draw judges from Florida, the Carolinas, and the Deep South.
Judges from the south will drive to Atlanta just as easily as the would Nashville.
I think this region (the Deep South) likely has a smaller number of judges to draw from. Tennessee sits on top of Alabama and Mississippi. We just got legalized Homebrewing less than 3 years ago and we are in the Bible Belt.
The selection of the competition sites pretty much depends on having a core group of people step up (contact the AHA) to organize the competition locally. Volunteers need to have an adequate pool of BJCP judges in the region for the competition. Volunteers pick the judging date from a range of dates available (March through April), and they need to make sure they don't have competing competitions, festivals, beer week events, spring break, or other conflicts that could hurt their chances to complete the competition.
That being said, there will be site changes for the 2017 NHC, as there are inevitably every year. Florida has requested to be an NHC First Round site next year, as has Kansas City. Typically the AHA gives first right of refusal to the existing sites.
Thanks to all of the people who have volunteered to put on the NHC over the last 10 years! I really, really appreciate your enthusiasm, and effort, and most importantly, your time and devotion to homebrewing. Cheers to you!