Even Nikki Haley, the woman who pulled down the Confederate flag?
People of color aren't mindless idiots who will suddenly start voting Republican just because they nominate a minority or woman.
Nikki Haley could certainly pull away white suburbanites who deem her 'acceptable' but she would not win significant minority support.
No one is talking about the GOP, like, winning outright pluralities of ANY minority group ... but there are no doubt
conservative minorities that are still voting Democratic purely out of a belief that the GOP is hostile to minorities in general, and a face of the Republican Party that is LESS outwardly (seemingly) hostile toward minorities would certainly improve with those voters.
Frankly, it's kind of paternally racist to assume otherwise ... there is as much ideological diversity among Black and Hispanic Americans as there is among White Americans, even if they are both currently finding themselves overwhelmingly loyal to one party.