Will the South Eventually Have a Majority of the US Population?

[Agonized-Statism]

Doubtful, some of that growth will reverse with the Great Climate Migration. We might lose New Orleans for good this year, and Houston won't be a safe place for the climate refugees for long.

[Agonized-Statism]

Doubtful, some of that growth will reverse with the Great Climate Migration. We might lose New Orleans for good this year, and Houston won't be a safe place for the climate refugees for long.

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.  

That's the thing. The rate of change will accelerate as we pass tipping points in the climate system over the next decade or so, and the bipartisan hostility toward a Green New Deal that said investment would require has only increased in the last four years. As insurance premiums skyrocket and more and more gets destroyed, the only really viable answer will be leaving. I agree that first this will initially mean shorter moves within the South (like the Katrina climate migrants to Houston historically that I mentioned or Floridians to North Carolina like you mentioned), but that faster-than-expected climate change will hurt the whole region as insurance companies panic. As this problem becomes undeniable, migration will slow (also, unrelatedly, the boomer cohort will pass in the case of Florida migration) and Southerners looking to move will get more cautious and look further afield. The Great Lakes states particularly will be much better equipped to take them in the near future as protectionism revitalizes industrial work there, and they become aware of their value and make an effort to diversify their economies as well.

[Agonized-Statism]

Maybe.  This is a reasonable scenario, but it all feels like it's set in an extremely warm world where it doesn't snow at sea level anywhere in the continental US.  This also makes me wonder if there would be a mega-resort developments in Alaska for retirees who enjoyed the climate of the present day Upper Midwest or Northern New England?

However, at the current rate of change, economic considerations like taxes and the cost of housing seem to dominate.  Parts of Upstate NY and the Upper Midwest do have the nearly free housing part, but are they ready to repeal or greatly reduce state income taxes and/or change their laws to basically let employers do whatever the heck they want?  Would it even be a good thing if they did?  Because that is mostly what's attracting people and businesses to the South right now.

I think climate migration and capitalism's race to the bottom are horrific personally, but I set that aside when making predictions. It's neither "good" nor "bad" inherently, it just is what it is, there's adaptive and maladaptive practices under the tyranny of capital that we choose to continue subjecting ourselves to.

Expanding tax bases would create budget surpluses, and considering that Republicans have been making headway up there for some time, politicians will absolutely jump on the opportunity for tax cuts. As the industrial sector of the bourgeoise strengthens with increasing profits and government support, they'll gain influence over politics there and cut into workers' rights. The Upper Midwest will "win" the race to the bottom in the end, especially if the South opts not to let coastal cities float away and has to raise taxes for infrastructure improvements.