Riots would cost the demo party too much. It would be a long time until they were re-elected.
If BHO loses, it will be a long time until they are re-elected.
McC would be POTUS for 4 years. Sarah would most likely be the next POTUS, and do so for 8 years. That’s 12 years before any truly viable Dem candidate will run - and by then, most every ‘60s-era Leftist will be retired or expired. The demo party power elite won’t care about preserving that path to control; by plan or by rage, revolution will be the only path they see.