One thing I wonder is that, even though riots will make the Democratic party as a whole look bad, might blatant disregard for civility turn off some Berners and make them a bit more sympathetic to Hillary? The Bernie supporters I know in real life probably wouldn't be too happy if his campaign (or those representing his campaign) promoted violence over the democratic process.
This.
I think there'll be yelling and shouting, but nothing more.
I think that the Democrats need new leadership. Debbie Wasserman Schultz has been so blatantly in the tank for Hillary that it has precluded the Democrats from nominating anyone other than a Socialist who looks like Father Time and isn't really a Democrat, and the repulsive spouse of a lecherous sleazebag who acts like she's owed the Presidency and plays the Gender Card nonstop. Let's get real here. Debbie Wasserman Schultz was the table-setter for events that have kept the Democrats from nominating a candidate whom folks might actually like that is mainstream.