Our society can barely handle a (minimum) estimated 0.7 million homeless.
We don't give a fuck about people who are disabled and cannot work and are on their own.
Half the country went completely insane when a virus threatened to kill tens of millions, and the government had the audacity to ask people to wear masks, and not shove horse dewormer up your butt.
When we get internal climate refugees, we will just double down on pretending that either they don't exist, or that the rapidly growing problem is being solved via wholly inadequate, understaffed amd underfunded nonprofits that would need to have 100 to 1000x the funding to actually address the current problem.
Optimistically we will get concentration camps.
Hoovervilles can't exist, those are are homeless encampments that the militarized police will clear out and destroy every 3 months.
Realistically, internal climate refugees will just be 'homeless people', left to wander and die.