I don’t think your assumption is correct at least not in Florida, for the first time in Florida History, Republicans outnumber Democrats in Registered Voters......
I agree that Red States are getting more red and the reverse is happening in Blue States...
California once voted Republican. That will never happen again. Other states - Colorado, for example - are also moving in that direction. But I cannot think of a single state that was once solidly Democrat that is now solidly GOP.
(Sorry for the pessimism. But I’m just calling it as I’m seeing it.)