I don't see it. The incident in New Orleans was for those white people, the "best case scenario". Reading from "Katrina's Hidden Race War" The psychology behind it was very simple. Us Vs Them with THEM being weak(flooded out of their homes, trying to get to safety, find food etc...) and US being the Whites that lived in that area patrolling their homes, land and resources from the incoming Black menace(From Their perspective) It sets up the ideal white racist dream situation.
The collapse of the US is totally different. Because it wouldn't just be "Black Savages" who've lost everything in a storm. You would have to worry about Everyone and that's only if your community bands together, otherwise it's neighbors, friends, and anyone else with plans of keeping their loved ones alive coming for that ass and the little you have that they don't.