I personally think they this is an inevitability in this country and every other one out other. This is because many places will literally be uninhabitable within a century given they’ll be underwater. Southern Louisiana is an obvious example as is Venice. What are your opinions on this given that this will invariably change things, especially regarding Florida.
Keeping places which are below sea level above water artificially, such as by the use of dikes, is a technology that already existed in medieval times, and is basically not challenging for a contemporary First World society. South Florida is growing much faster than the United States as a whole, and absent mistakes made by political leadership I sort of expect that to continue be the case throughout my lifetime. A pattern you're seeing in lots of large countries (certainly the US and China) is migration from colder to warmer areas, and I expect this will be the predominant form of climate migration in developed countries. (In developing countries, yes, things might be rather different).
Water crises in the West might indeed lead to back-migrations to the East depending on how well or poorly resources are managed -- my understanding is that, while SLC and Phoenix are not unsustainable, their resources do require careful management. But the main threat to New Orleans is political mismanagement, and the main threat to Miami is (potentially) having the misfortune to get a city government that would work like New Orleans'. But I expect Miami to be a significantly larger city when I die than it is today.
Such an engineering project in southern Florida should be technically feasible, however I am skeptical 21st century America has will or foresight to engage in such an endeavor. Which feels ridiculous given the consequences of not Netherlandizing south Florida, but I'll believe when I see it. Also, the intrusion of salt water into south Florida's water table is a unique problem that dikes and sea walls won't fix. I honestly expect Florida migration to turn net-negative by next decade
