November is still a LONG way aways, so there's still plenty of time for the Democratic party to consolidate and get on the same page. I think it's not uncommon for things to get heated in the primaries because by nature it pits the party against itself. But afterwards, parties obviously have to come together again for the national election.
More than anything I think the "Bernie or Bust" stuff was just venting. Unless the sexual harassment stuff against Biden really blows up (and so far it hasn't even come close to that), I think most progressive will vote for Biden to avoid another 4 years of Trump. It wouldn't make sense for them not to.