It's the people who live in big cities with large populations of gibsmedats who would be in severe trouble. However, if they get to the more conservative (and armed) suburbs, the mobs again will be in big trouble. But that's also assuming there will be a complete breakdown of the authorities.
In the end, I doubt even with a major power breakdown, that mobs will be able to get too far. Even with the major power breakdown, most whites (at least in conservative areas) would band together to help each other and shoot savages of whatever color. I do not see a case where it's every citizen for him or herself.
What I hate, in my advanced years, is that is a scenario that is even possible if not probable.
How many white people are you expecting to kill?