The answer is "We don't, but we know they will happen."
The thing is that we are well past the point where non violence will cause any social change. The cops don't give a fuck about non violence. Mayors don't care about non violence. The media doesn't care about non violence. And the billionaires who buy the elections these days could give two shits about non violence.
But burning shit? Yeah, that gets people's attention. And the buildings that get burned tend to be owned by rich people. And rich people can claim insurance on those buildings - so insurance companies care about actual violence. And, politicians listen to insurance companies. Even rich people listen to insurance companies.
So, riots make some sort of sense. Look, man, people don't have jobs and if they do have jobs they tend to pay shit. Imagine working well over 40 hours a week and still having to be on food stamps. Now imagine that while also wondering if on any given day you or one of your friends or neighbors is going to be beaten or shot to death by cops - and that the cops who do it will probably get away with it.
How long would you put up with that shit until you thought to yourself "fire is something people pay attention to."
So yeah, there will be more riots. Probably Detroit first, then Chicago and then L.A.
Nobody wants it, but it's blowing in the wind.