This is something that could happen in theory, but I think the breaking point is a lot further out than assumed. The Gulf Coast continues to have huge net population gain. It seems that there will still be large cities, just completely dependent on complex dike/levee systems each summer. Think about how Amsterdam was a seabed a few hundred years ago. If it can be dried out and kept dry, with enough investment so can Miami and Houston until/unless it becomes more economically/aesthetically attractive to leave.
Again, there's a point where it breaks down, but keep in mind most of these people actively want to be in a place where it never snows. They aren't going to actually retire to the Great Lakes until/unless things are so far gone that Michigan or Upstate NY has a Mediterranean climate. They would end up on a beach in NC if in 2060 it has the climate of present day Florida.
So, when millenials and zoomers are retiring? Politics will be very, very different in 2060 if/when NC appeals to the retirement of folks.
