>New Orleans obviously needs help way beyond anything that's ever been needed before after a hurricane in the U.S.

I think if New Orleans was a normal large town, small city that it would just be abandoned, but because of its special status as a cultural place, it will eventually be rebuilt.

Take a look at this hurricane from 1900, it also list an even bigger one that happening during the American Revolution.
http://en.wikipedia.org/wiki/Galveston_Hurricane