There is a lot of talk about how Sanders, not going to win the nomination, ought now quietly withdraw before the Democratic National Convention. But why? With roughly 40% of primary voters supporting him, he and his faction ought to get something, especially if the Democratic Party expects his supporters to turn out for the party, and work on Clinton's campaign.
There is symbolic weight in walking into the convention with nearly 1900 pledged delegates at your back, even if Clinton has 2200. (There are approximately 600 "superdelegates," Democratic officials of various sorts, who are swing votes. Clinton needs only 80 of them to clinch the nomination.) Back when, before the internet, the power of those numbers was immense: delegates and reporters would walk into a crowded hall and see the support. Television made that visible to the whole world. Even now, seeing those numbers, seeing those people, carries weight. I hope the Clinton campaign and the Democratic leadership will pay attention.