So, I actually disagree that the DNC would refuse to make Bernie the nominee in the event he has only a plurality. I actually do not think the DNC is as anti-Bernie as people want to pretend it is. If they were, they'd have changed the rules to make it harder for him to run, not literally give in to almost all of his demands. If you wanna fuck Bernie over you do it WAY before the process starts, not at the finish line. So, that makes no real sense to me.
Like, I totally think there are people the DNC would rather have anyone else as the nominee than Bernie. Without question. There are people within the DNC who would rather have Bernie than Biden. For a big chunk of the DNC a Bernie nomination is going to be a make lemonade out of lemons situation, but they're not totally stupid. What will happen is they'll force concessions out of him, probably on the Veep selection. Probably a few platform things as well, but it would be worked out way beforehand.
I doubt they even let it go to a second ballot. Let a few states go so each of the people who ran get their names on the roll, especially Pete as the first openly gay candidate to win delegates, and then move to nominate Bernie by acclimation.