Thats not gonna to happen. The gun issue wont allow Blacks to vote for Sanders, since he is from Vermont. BLACKS are urban.
I think this speaks to a greater issue, that the Clintons are still an institution within the Democratic Party, especially among the core establishment, especially among African Americans. White millennials didn't grow up with Bill Clinton, and don't remember eight years of economic growth and peace. Bernie Sanders is a young, white phenomenon.
Hilary rides the coattails of Bill, and Bill is beloved and cherished. He might as well be J F freaking K. The media and internet frenzy around Sanders forgets this.