They could be fixed, but political posturing and the need for individual power will probably corrupt the process. Not all of this will be intentional, but just a by product of the way humans interact.

Alot could be done, but it will have to be things the government insists on. Things like stronger levees and better pumps (pumps were earth 20th century technology, parts could only be made, not purchased! Okay, not a big thing, anything over 20 years probably has to have parts made).

Perhaps the biggest thing would be increasing trust in local government. I have heard stories of corruption in New Orleans and Louisiana, but I don't know that for sure, as I've never lived there. If there is in fact, people aren't going to trust anything their local government says. "You better evacuate, because it's going to be real bad" "Yeah, right, just like you said that other thing was real bad. Turn out to be nothing. I've lived here for XX years, and nothing has happened". Oh, and educating ignorant people about things.

It can all come back together and be better, but it starts by accepting personal responsibility for your actions. This goes for the Mayor, Governor, and individuals. If everyone had done their part, this mess would not have happened. You can point fingers in every direction, but at some point an individual has to make a decision. Sometimes you just have to go it alone!