This is how he wins. Bernie can't get the establishment vote, the elderly vote. They want something he doesn't have, and he'll never win them. But Bernie has always been an active defender of civil rights. He marched on Washington. He organized sit-ins. He was arrested for protesting. Clinton's support of civil rights, contrariwise, is weak and based on lies. The problem is, they don't know. If Bernie can show Black and Hispanic America the facts, he'll win categorically.
Ta-Nehasi Coates recently declared he will be voting for Bernie. While he is against endorsements (see linked article), I think this is a somewhat important thing to happen considering his recent criticism of the candidate. Ta is an influential person, whether he wants to be or not, and I think this public declaration will cause people to look more closely at Bernie.
And Clinton's campaign is certainly responding to this threat. Today, my social media feeds are blanketed with blurbs questioning Sanders participation in the civil rights movement and alleging he dodged military service.