They'll have to rebuild SOMEthing SOMEwhere there, because New Orleans is/was too important and strategic a port location to just let the land and sea reclaim it. But turning it into New Venice won't help when the 25-foot storm surges swamp it. Maybe the more economical answer is to build a whole new port city on the north shore of Lake Pontchartrain or some other area location that is off the Delta and above sea level and that offers a land-buffer from the worst of the Gulf storms.

Whatever they do ultimately, they have to take care of the immediate need to repair the levees and pump out the sludge and rescue whoever is left alive to be rescued and count the dead and salvage the salvagable and let the banks and corporations empty their safes. After that, I'm all for filling in the "bowl" below sea level and either building on top of it or moving the city altogether. Sure, it would be immensely expensive, but it would be a better investment than putting N.O. back together the way it was (with higher levees) and waiting for the next big hurricane to wash the city and the money away again.