The story that he's "backtracking" is BS. His "C'mon, man, you ain't black!" cack-up was so profound he can't get out of it, and if he doesn't pick a black (woman, because he stupidly made that promise) he'll lose a bunch of AA votes. He doesn't start with the natural Rat advantage of 85% of the AA vote, because Trump really is attracting more black votes than Rats usually do.
This is to be expected when the Rats are in a perpetual cycle of cobbling together factions of minorities, where every calculation comes with a balance of the promise of associated gains versus the risk of losses. They've been doing this since before I became a spectator of the game.