Most of what I've seen leads me to believe that will be the case this time around. But take a look at how Sanders' addressed a question about that on TYT yesterday:
Uyger: But! You have convinced them that Hillary Clinton is the establishment candidate. If you were to lose, and the Democratic Party comes to you and says, "Okay, now take this movement, that is full of energy and is against the establishment, and make sure they vote for the establishment candidate," what do you say?
Sanders: Well, you know, what I say— Number One, I'm not big into [air quotes] being a leader. You know, I much prefer to see a lot of leaders, a lot of grassroots activism. Number Two, what we do is together, as a nation, as a growing movement, is we say, "All right, if we don't win"—and, by the way, we are in this thing to win; please understand that—"what is the Democratic establishment gonna do for us?"
Uyger: Oh, that's interesting.
Sanders: All right, for example: Right now, you have a Democratic establishment which has written off half the states in this country, you know that?
Uyger: Mm-hmm.
Sanders: And they've given up on the slate in the South, the Rocky Mountain area—are they gonna create a 50-state party? Are they gonna welcome into the Democratic Party the working class of this country and young people, or is it gonna be a party of the upper middle class and the cocktail crowd and the heavy campaign contributors? Which to a significant degree it is right now. You know, I've talked to Democratic Party leaders and said, "You know what? Instead of going around and raising all kinds of money from wealthy people, why don'tcha meet in some football stadium and bring out fifty, a hundred thousand people; bring the damn Senate in there, Senate Democrats, and start talking to people—ask them what they want you to do. How about that?" Better? Radical? So, in other words, if I can't make it, and we're gonna try as hard as we can 'til the last vote is cast, we wanna completely revitalize the Democratic Party, and make it a party of the people, rather than just one of large campaign contributors.
http://www.shakesville.com/2016/03/this-is-getting-real-old-sanders.html
There's a ton to unpack right there (He's running for leader of the free world but isn't into being a leader?), but I don't see word one about any support for the eventual nominee. Melissa's take down at the link is excellent.
As part of Hillary's "cocktail crowd", I naturally recoil at the notion of governing via stadium mob. Is that really where he plans to take his revolutionaries? He has just folded the significant Democratic majorities that already voted for Hillary Clinton into the opposition to his Movement. Of course, it's all as vague as his plans for an encampment beneath McConnell's window, but there isn't even a whiff of party unity in there. What am I missing?