The biggest draws as fighters have been, going by the numbers (in no particular order) McGregor, Rousey, Anderson, Jones, GSP, and Lesnar. That's two out of six being black. Statistically, given a tiny sample size (6), that's pretty much even. Moreover, the number of white fighters (and champs) is much larger than the number of black fighters (and champs), so the chances of a black champion being popular is higher than that of a white fighter (ie popular black/total black > popular white/white).
So whether he's a big PPV draw won't have anything to do with his race. Even being foreign might not matter, given that two of the six - GSP and Anderson - aren't American.
And in fact it'll come down to his personality and his ability to stay on top long enough to get name recognition. MMA is a tiny niche sport (even GSP, very popular in MMA terms in Canada, got less than 1% of potential Canadian PPV's - if someone like GSP who was champ for a long time got 1%, think about how little name recognition most MMA fighters get).