I think this is good. The United States is the third largest nation by area on the globe. Unlike The Netherlands, there is no reason to have a major U.S. city with substantial portions below sea level.
In the medium-to-long run it will be cheaper to buy out those living below sea level via eminent domain so we can stop spending money on levees, sea walls and pumps. New Orleans should zone all below-sea-level areas non-residential/non-developmental, and prevent rebuilding where it has not occurred.
Then convert the empty land into parks. Parks can flood occasionally without harm, as those in Sacramento demonstrate clearly. Most of the year they will be available.
