In other words, a substantial number of Bernie bots were never going to vote for Clinton. Old, white, racist, sexist. When Sanders bailed, it didn't take much to send them to Trump.
That cannot happen this time around. The Dems should refuse to allow him to run as a Democrat. He isn't a Democrat and will never be a Democrat. He just wants to leech resources away from the Democrat, and when he loses, refuse to support the nominee.
And Tulsi Gabbard is waiting in the wings. She's just a Republican with, again, questionable Russian ties and a guru who is absolutely insane. She needs to be voted out, too.
I completely agree that the Republicans need to be incinerated. Burn the party down and leave them wallowing in despair, wondering how many decades it will be before they get to anything approaching power again. We need to be rid of ANYONE who thought Trump was a good idea or, even if they didn't, did nothing to stop him. As you say, 100% is probably impossible, but we need to vote out as many as we possibly can.