No, sadly, I don't see riots before Brexit.
I can, however, see riots if the predicted doom of no deal happens.
It's interesting how few people really consider the idea that shortages can happen. I fall into this, I know that most of the food we consume in November /December is imported, I know that Brexit will interupt inports/exports to some extent, so of course logically there will be some problems, but I find it really hard to take seriously that it won't just get sorted out. I know that's my comfortable middle class bubble talking, and that I do need to think about stockpiling basics, but it feels silly to do so, because things usually sort themselves out... (as it is, I can only bring myself to buy extras of stuff we would normally have in, like tinned tomatoes/pasta/rice/frozen peas etc, so if it's all fine, it's not a waste of money - I've just spent part of November's food budget in August, I know I need to think about bottled water and torches etc, I just can't help feeling deep down it's a waste of money...)
Lots of people are like me, sort of convinced it'll all be alright. I'm not the rioting type, but I do worry if it's not all ok really, then the shock of that will cause a massive outpouring of anger. How that anger is directed will be hard to predict.