Levees don't work in south Florida. Well, they work to stop water that comes in horizontally above ground level, but in south Florida floods usually come in by bubbling up through the porous ground.
Worldwide, cities on river deltas face problems. Mostly in Asia. New Orleans is the only US city built on sand flatland at the mouth of a huge river. Asia has several of those.
New York is building a seawall around lower Manhattan. The West Coast isn't that vulnerable because the coast is mountainous. Even in areas of LA that look flat, go a few blocks inland and you're up 10m or so above sea level. The parts of SF built on fill may have problems.
This isn't the end of the world. But some cities will need rebuilding.
[1] https://www.thestoryoftexas.com/discover/texas-story-project...
[2] https://en.wikipedia.org/wiki/Raising_of_Chicago
[3] https://mdc.maps.arcgis.com/apps/webappviewer/index.html?id=...
In the USA, is that even possible anymore? I've been to both Galveston and Chicago, and you can see oddities here and there in some neighborhoods. In many cases, homes were not actually raised - the main floor became a basement and above it new doors were made into the existing walls!
In a lot of locations, you cannot have a basement and get flood insurance. So what poorer people did in Galveston and Chicago is no longer an option.
There are some problems with the assumption of a flooding crisis. The historical record from tide gauges have been retroactively altered over time, to make apparent level rises in modern times worse and level rises in older times less so (this seems to be a common theme with data from climatologists - they rewrite historical datasets to make the magnitude of changes seem larger).
Additionally at some point they switched to satellites and stopped using tide gauges but it's not clear that's more accurate and may actually be less accurate (but it did make the rises seem larger, so there's a conflict of interest there). In particular, NOAA and NASA disagree by a large amount on what the actual level of rise is. NOAA say it's about half what NASA say it is.
But you are right that it will keep rising for a thousand years or more. But now at that timeframe we're talking 6-12 meters or more.
This is all in the fairly conservative public estimates that so far have underrepresented the pace and scale of change.