Aside from the houses, think of the problem of dealing with furniture, clothes and bedding. Vehicles. Electrical/electronic stuff. That's an immense landfill.
Somewhere in the coverage it was said that if everything is working, and no more water comes in, it would take at least a month of fulltime pumping to get the water out. Before the pumping can begin, some sort of effort is needed to get motor-generator sets in, since it will be weeks before they can get the regular electric supply set up to the pumps.
I guess it's a cold-blooded view, but they might as well start the dredges and fill the bowl and start over, some years from now.
The human factor is that of dealing with a million refugees for some unknown period of time--and not a short time.
Art