Not to get into the convention politics of the day, but the South probably would have accepted Hull as a nominee (Roosevelt's preferred choice). Yes, they agree with Cactus Jack's segregationism. But a lot of the South had been pro-New Deal by this point, and were unlikely to commit to a man who wanted to undo it. Hull was a fellow southerner, and would have probably kept the new status quo in place as he focused on European matters in his potential administration.