The black vote is baked into the cake. A Hispanic nominee might garner the GOP about 40% of that vote, sufficient to win, all else being equal.
Black Americans and Hispanic Americans are clearly Americans.
But they do not vote for Conservatives when they have a clear choice.
And having a Black Conservative candidate does not help, either.
In 2012, Allen West's new Congressional District had about 30% non-white voters, plus a large bloc of retired Jewish voters.
Those two voting groups refused to support West, and West lost a close race by about 0.6%.