It was over in March. Tonight's win still won't calm down his supporters though.
Cue the accusations of fraud.
Two things need to happen, and not necessarily in the following order:
1.) Bernie needs to demonstrate to his supporters that if he is willing to crawl over broken glass to ensure Hillary wins in November, so should they.
2.) Hillary should select a running-mate to demonstrate her willingness to reunite the party after a long and bruising primary, preferably someone that the more skeptical Sanders supporters can rally around. And not just for symbolism -she needs to pledge that whoever she selects will have a role as key in her administration as Joe Biden has in Barack Obama's White House. She has to show that her running-mate won't be just another White House ornament.