The California analogy is not entirely accurate. No one will ever build a system that can protect California from earthquakes, so if you want to build in Cali there is no reason to wait. If NO is rebuilt, the water containment system will of course be upgraded to withstand cat 5 hurricanes. As a person looking to build a home or business in NO, your choices are to start construction now, or wait until the upgraded containment system is finished a few years from now. I'd bet the vast majority of people would rather wait a few years than gamble on the current levees.