I don't think Sanders would've had much problem with the minority vote either.
He was gaining with that crowd as is, doing things like webcasts with rapper Killer Mike. He was also more exciting to younger voters, that and a distaste for Trump would've worked to his favor with establishment Democrats over time. People were awfully butt-hurt in 2008 as well when Obama got the nomination over Clinton, but they all rallied around Obama by Oct '08.
People didn't dislike Bernie, they just didn't know him as well as they know the Clintons, give him a DNC and several more months to campaign on and he would likely have gotten similar numbers as Hillary with minorities. There's nothing intrinsically popular about Hilary with minorities and as was said above, Bernie has a terrific history in the civil rights movement. If it was that much of a concern he also could've just ran a minority VP pick if you want to be all calculating about it.
Minorities will be the majority in America soon anyway, so the Republican party will eventually have to adjust to that, Trump's path is not a long term formula for anything, it's more like the last gasp of preying on the anxities of a shrinking demographic. It won't work forever because very 4 years more of those people die off, and the younger portion of America is already more than 50% minority. So dog whistle racism is not going to work forever.
