I doubt it. Party loyalties run deep, and the African-Americans who are most likely to vote are the one's most likely to be committed to the party. Also, if Democrats put an African-American on the ticket, it's bound to help them this time.
It's to be expected, though, that the Black turnout will be lower than it was in 2008 or 2012. Hillary couldn't get as many Black voters to go to the polls for her as went for Obama, and that did her in. It will be similar this time.