It benefits POC for Bernie to stay in the race.
As the Nineties proved, Bill AND HRC will always abandon POC once they think they no longer need them.
That's why POC got nothing but betrayals and attacks from them after Inaugural Day, 1993.
Hillary will only offer POC a decent deal as long as the nomination is still in play. The nomination only remains in play as long as Bernie keeps running and continues to slowly cut into HRC's lead among POC.
Bernie Sanders has always been a stronger antiracist than HRC in terms of his actual record. He shows his antiracist commitment by fighting on for social and economic justice for all despite his losses among POC in the early contests.
If Bernie withdrew now, HRC would immediately start in on the "tough on crime" rhetoric and start posing with rows of (white) cops behind her. "Tough on crime" and "Law and Order" can only be code phrases for "Institutional Racism today...Institutional Racism Tomorrow...Institutional Racism forever".
In other words, if Bernie gets out, black votes WON'T matter to HRC anymore. She'll ditch you again and go all 'you have nowhere else to go" on any of you who call her out on it.
Bernie made early mistakes, but he has corrected them. Sensing that POC distrust him, Bernie, if nominated and elected, will work twice as hard for POC to earn that trust.
True Sanders supporters(btw, the 'bros aren't Sanders supporters-they are wreckers allied with Ron Paul)respect POC and fully defend the idea that black votes matter. That's why we are still trying to win those votes, as we have tried to win them throughout the campaign. Our social AND economic justice proposals would do more for POC than HRC's It would not show any respects to black or Latino voters to get out before millions of black, Latino, Native American, Pacific Islander American and Muslim-American voters get a chance to have their say in the process.