Mississippi, Alabama, or Oklahoma.
Mississippi had a surprising swing towards Obama in 2012, so that's out, IMO.
Assuming blacks get fully onboard within the next decade or so, I would say Utah or Idaho.
If blacks nearly universally support it by 2020 or so, it will only take 1/6th support from Mississippi's white population. That shouldn't be a problem by 2020 or so.
This won't matter unless Dems can get control of the Miss. (or Ala.) legislature.
Southern black support for SSM will rise, and will be above Southern white support, though I doubt it will be near universal anytime soon.
