I think this is an unsustainable strategy in the long term. Many of America's biggest most profitable cities are on the coasts. With rising sea levels many will be at risk. Some (eg. New Orleans) already are.
On the other hand, investing a little money in terraforming never hurt anyone and has a proven track record.
there are high and low density locations. The dutch have proven that very little technology can protect land from the sea. I'm not opposed to special cases, but the coastline is _huge_. I don't believe we can protect all of it anymore.
Perhaps it was an option at one point, but we're past that point (in my humble opinion. i'm not a climatologist or an economist, i'm likely full of shit).
i think it's too late to reduce carbon emissions, and that requires global buy in. I think it's too late to build a wall along the whole coast. I think there are obvious places for exceptions, but 99% of the coast is going to sink. let's just own that and make the change as painless as possible.
The Netherlands - being situated in a delta- once had a disproportionately long natural coastline. One of the strategies employed is to shorten that coastline dramatically by strategic placement of walls. Of course, in a country like the USA, not even all of the coast requires additional protection; only parts of it.
I do agree with you that certain cities (like Miami) might be difficult-to-impossible to protect with current technology. Other cities (like New Orleans) have well-known challenges with well known solutions, and there is absolutely no reason why people couldn't protect them.
What is needed is for people to put together the political will, attitude and organization required to survive and thrive in those kinds of conditions (with a strong push towards prevention rather than recovery).
That too has already been done many times over the centuries; and there's no reason to believe that Americans (or Louisianans) are in any way inferior to other peoples.
Which is not to say I agree or disagree with you completely:
On the other hand, investing a little money in terraforming never hurt anyone and has a proven track record.