I'm fascinated by the idea that voting against Trump is something that only establishment politicians would do.
I'm also fascinated by the laughable idea that Trump, who readily admits to using his wealth to procure influence in policy-making and other realms of existing governmental structures, is not an establishment candidate. If Mark Cuban is the Establishment (as suggested in the OP), Trump is as well -- necessarily -- even if he's fooled a bunch of scared white folks into believing for now that he doesn't.
And if Candidate Obama said some of the patently false things that Candidate Trump has offered on the stump about basic cons utional issues (supporting Article XII, for instance), he would have been absolutely skewered by the Right. (Obama was absolutely run through the ringer for his "57 states" comment). Indeed, when Candidate Kerry said he was for the war in Iraq before he was against it in 2004, he was pilloried by the Right as a flip-flopper; Candidate Trump admits he was for the war in Iraq before he was against it, and he's praised by the Right as a man of searching intellect and discernment.
Whatever is true about our politics any more, the one thing that is absolutely true is that actual principle has no real place at the table right now.