Trump won anyway though, the problem is it would have given establishment Dems yet another false excuse for why Hillary lost. The reality that none of the establishment wants to face is that this election shouldn't have been close, if they had run another candidate we likely wouldn't have Trump as our President right now. The party officials did everything they could to make sure Hillary won the nomination and they are as much to blame for our current situation as Russia or racist voters or anything else.
Honestly I want someone younger who can better explain their vision to be the nominee next time around, I love Bernie but the guy never once seemed to give us a way to actually accomplish his goals, we need someone who can not only detail how they'll be able to accomplish what they are pushing but also be credible (which HRC wasn't) and not be someone who is in bed with bankers and other special interests.
I also hope the Dems really push campaign finance as one of their big pillars next time around, they need to get the country on board with getting money out of politics, that may mean getting a lot of the old guard out and having them face primaries by newer more progressive Democrats because something needs to change and a lot of the Dems that have been sitting in the senate for a long time seem just more like Republican "lite" than true progressives.