I think it'll happen between election cycles. Trump and Hillary are both widely hated, and neither of them is going to do much good. The bubble is gonna pop, maybe accompanied by another major recession(maybe not directly in the US, but a bad enough recession in Europe will still cause major problems), and people are going to get mad. Already, most people know that the political system does nothing for us. It will just be more and more evident.
The real question is, will it be France 1968 or Russia 1917(February, of course)?