Well right now he doesn't have to say nice things about her but if he doesn't win hes going to be expected to tow the party line. Hes likely going to have to come out supporting Clinton in positions that are going to be against the interests of his base. I don't think hes going to be allowed to come out and say that yeah Clinton is shit, I agree, she is bought and paid for by big business and corrupt as hell but the other guy is a crazy loony so vote Clinton. I could be wrong but I don't think that's how politics works.

Sanders basically has to either withdraw his presence from 2016 presidential election and re-purpose his movement into local elections or go independent to maintain the movement. Otherwise he will be forced to actively endorse and promote existing Clinton positions which suck and will loose him credibility. VP sanders would also kill the movement because then he would just be a puppet in the Clinton campaign.

Basically I think either the movement is re-purposed to support Clinton and it dies (because Clinton excites absolutely nobody) or it needs to be split off from the democratic party and I'm not sure how that would happen.

What kind of scenario do you envision that allows the movement to continue on its own?