I suspect the fix was in while Hillary was still SoS or even before then. There was no way anybody but Hillary was going to be allowed to get the nomination. Her money and name recognition convinced the DNC that it had to be her, and all other Democrats would be scared away from even running. Bernie's lack of membership in the party wasn't the reason; O'Malley got the same disrespect and disregard (and he, too, complained, also to no avail) even though he's arguably a bit more "establishment" than Bernie. If Bernie hadn't been involved, O'Malley likely would have done a fair bit better but he still wouldn't have been allowed to win. It was always going to be Hillary.
And that's why I'm not depressed. I'm a bit irritated at the condescension, disrespect and gloating the Hillaroids on DU have been dumping on Sanders' supporters for the last six months, after it started looking like Bernie was at least going to make Hillary have to work a little harder for her win; but it's no big deal to me. They're strangers on a message board, and most likely a few of Brock's paid trolls. The main thing, though, is that Bernie has stirred up something that won't go away.
At this point I suppose the campaign will have to decide whether and when to concede and what to do after that. It would appear that there are two goals for Bernie and for those of us who have supported him: 1. In the short term, prevent Trump from winning the GE (people can vote for Hillary or not; that's up to them; but either way we have to do an anti-campaign to emphasize what a deranged, dangerous asshole he is); and 2. Keep the movement going after the election. Don't let the election of a centrist/corporatist defeat what Bernie started. All politics is local, they say; what needs to be done in the long term is find and encourage real progressives at the state level and get them elected.
So although the gloating on DU is annoying, I'm OK because I knew Hillary was always going to win; you can't beat city hall without building a movement. Instead, I'm looking forward to crushing Trump like the disgusting insect he is, and then digging in and getting progressives elected.