The Democrats will make peace. Clinton will buy off Sanders by giving him a major voice in the party platform and will unite both Sanders and Warren behind her by giving them a say in the VP selection.
Don't forget it wasn't too many weeks ago that they were predicting this for the Republican convention.
We don't know what some of the more radical Trump supporters (Gary Forbes, Roger Stone and that ilk) would have done had Trump not won it outright.
Bernie, that red-diaper baby, sees his communist revolution and, face it, he has absolutely nothing to lose by promoting it.