I'd be amazed if there was rioting or any kind of significant unrest as a response to the event of Brexit not happening.
What there could be however is a deepening of already existing feelings of disenfranchisement which could indirectly contribute to creating the conditions for unrest further down the line.
And as
killer b suggests it would sustain a constituency for a populist right party to exploit. Especially given the Left's abandonment of this constituency and it's concerns.
However neither of these scenarios are dependent upon a "Brexit Betrayal". They're both already here.