Is Mississippi getting blacker?
36.66% in 2000, 37.00% in 2010. Hispanics are growing too (like everywhere else), but this is all probably neutralized by the fact that Mississippi whites are becoming even more Republican with yellow dog types dying out, like Gene Taylor found out. It's highly unlikely this state will change much politically on presidential level in foreseeable future.
Popular, moderate Democratic incumbent (like Clinton in 1996) could win Dakotas if he decided to target them intentionally as "crown jewels" in a successful reelection bid, but that's unlikely because Dakotas are not worth much electorally.
You can't get much more republican than 90-10.