2016 Postmortem

The point must be made that 'the establishment' is one of those lazy knockout terms that has become common currency. Whoever happens to be in charge is 'the establishment'. In other words if Bernie's lot were successful and eventually commandeered the DNC they would, ipso facto, be the much-derided 'establishment'.
There was a left wing guru in Britain called Moss Evans who is widely credited with throwing the May 1979 general election to the ultra-right wing Margaret Thatcher by spearheading massive industrial unrest the previous Winter despite calmer heads within the broad left warning him of the long term consequences.
One of them was to ruefully remark after Thatcher's victory:

The political education of Moss Evans has been very expensive indeed.

I would say that the political education of Bernie and the Bernistas has been very expensive indeed.