Fam I respect everything you said here, but as a Bernie supporter who kicks it with a ton of lefties and tries to be involved in events and discourse as much as possible, I do want to offer some responses.
So when you say he wants to move the party left, but the powerbrokers will only let him go so far, 100% true. They're going to do everything in their power to slow him down. But I think what we've seen from 2016 to now is a snowball effect. The momentum he started won't stop with him. Each member of the Squad is proof of that and the party as whole has already shifted left in terms of rhetoric and offerings. The 2016 platform for Bernie has played a big role in shaping two of the front runners' agendas (Warren and Bernie) while both Biden and Buttigeig (the moderate front runners) are to the left of Hillary with their platforms. So just the pressure that Bernie created has pulled the party further left than I think powerbrokers wanted.
On top of that, since the DNC blocked out any consultants from supporting progressives running against incumbent Dems, the lefties inspired by Bernie have had to develop their own infrastructure. So there's gonna be a parallel group of lefties who fundraise differently, strategize differently and approach power dynamics without having to bow to the typical party power structure...an example of this would be AOC refusing to contribute to the DCCC to support other campaigns, but instead she raised more money and created her own support system for the candidates she supports. The DCCC was stonewalling candidates that share her goals, so she supported those candidates with the money that the DCCC would have used to beat those people.
I don't agree that he used the Dems to give himself a higher profile, but it's open to debate. He's caucused with the Dems for a very long time and even heading into the 2016 elections he didn't actually intend to run. He was part of the draft Warren movement and only got in when Warren decided she wouldn't. His stated goal was to pull the party left and he succeeded there but he didn't take winning seriously until it was too late. Even he didn't expect this thing to blow like it did. And I attended a kickoff for him, it did not look like he'd blow like this. First event I attended had maybe 15 people present and then a few months ago the last event I attended was his return rally with AOC, 20,000 strong.
So I get that the idea is "he's using our brand but won't bend the knee" but because they've been trying to cut him out, new ways to organize and win elections have been building. Our Revolution, Justice Democrats, People's House Project and others are working to shift the Dems and bring in new blood. People 35 and under massively lean toward the progressive side of the Dems. The party is moving towards Bernie's side of things and I think that movement is going to continue. He might not win and they may get that block off, but the Boomer's will age out sooner than later and the progressives will have built their own structures to compete with the DNC's monopoly of party power.
Edit: Also while obstruction is likely for Bernie's whole agenda. I'd definitely say check out the American Prospect's Day One Agenda series where they spoke with campaigns and legal scholars about things the next president could pass without Congressional Approval. The biggest two imo were reducing drug prices and forgiving student debt. But there are strategies to get pieces of the platform passed even with Republicans and some Dems obstructing everything. Warren put out a strategy for student debt last week specifically and Bernie has alluded to the same concept as well.
