can a large swathe of the electorate really be convinced he sincerely tried to get a deal?

A large swathe of the electorate is informed by billionaire-owned media and fakes on social networks, and have shown to date a remarkable propensity for believing any nonsense that is thrown at them.

he is quintessentially part of the establishment

We see him as that, I think large numbers of people don't. He's a dab hand at scrambling his image.

Whether he'll succeed, I don't know. But even today's news confirms my belief that he will seek to get the EU door shut in his face as rapidly as possible. He'll then have three months in which to attempt to swing Brexiteer voters behind him. In which his advantage over Farage is that he's actually in Number 10 and can deliver the wished-for goods.

Things are going to slide, slide in all directions
Won't be nothing
Nothing you can measure anymore
L. Cohen