Steve I would agree there, no flood insurance, or if you can get it, the premiums reflect the fact that you are high risk.
Skinny, the French Quarter believe it or not is one of the highest areas in the city, there are only a couple others that are, one is a cemetary (this one the people are actually buired below ground, not in a crypt)
As for the buildings up to the soffits in water, once you strip the building to the basic shell, you can wash the wood, and then seal it to prevent the toxins from leeching out. We use a product called Killz to seal wood after a fire repair, and smoke is one of the hardest things to keep in.
I think the biggest problem facing NO is the drinking water issues, the water system may be too damaged to just repair, we don't know that until they start working on it.
Now to get to the Netherlands. The storms they deal with there are not hurricanes, however, they have to deal with the North Sea storms, which can be worse, and more frequent. That is one reason they did do something to prevent the storm surge from flooding the cities. See
link for one example they have done. I was trying to find the undersea barrier they built as wel;l, but was not able to.