Dems need a real leader that can pull everyone back together, inspire Dems again and has enough of a backbone not to cave under Trump's particular kind of pressure.
I don't see it happening... there's too much of an ideological split between the centrist and progressive voters.
First, neoliberalism is irreconcilable. For all the old guard calls themselves pragmatic, centrist, etc and tries to distance themselves from being perceived as driven by ideology, that is an ideology they will take to their graves. And so long as that's the case, they will not win over progressive voters, except out of critical desperation to avoid the worst possible evils.
Second, the centrist old guard needs to drop its habit of treating politics as a game with win conditions separated from actual political goals. You can't have one of the most recognized names in the group saying "We need to adopt the right's stances on immigration in order to win elections" as the right is setting up camps and threatening mass slaughter. That will only work for someone who does not actually care about anything but the tribal aspect of seeing that chair labeled D. For the progressive wing, and anyone who actually cares about their platforms, if nothing you care about is being earnestly represented in the end, then you didn't win the election.
This is not a rift that can be simply tolerated for the sake of pragmatic alliance, as with the religious right/libertarian/alt-right alliance. There's not enough alignment of desired outcomes, and often direct contradiction. Whichever path the Democratic party chooses, they're going to struggle.