If I were to Hazzard a guess, this seems bad for the democratic party nationally. These states will be republican strongholds for at least a generation or two (especially sc and la,) and the only one I see not being a safe republican position is a swing state Georgia. This leaves the DRC with Virginia, the very deep south, and the planes. That just doesn't feel like the electoral base of a national party.
All three of them probably see more national investment, and it's very likely there's no great migration out of the south, but one to different parts of the south. Which strengthens them in the house and further weakens the democrats.
Otl the party switch was started when the democrats were more receptive to immigrants, which pivoted them to an urban party with Wilson's economic progressivism (and then FDR solidified it,) which is why they became pro-civil rights (outside the dixiecrats who pivoted to the nativist gop.) I don't know if that would happen ttl, since the Republicans still have such a strong base in the cities of the south