I disagree about minorities. Presumably, he'll do better than Romney with Hispanics. In addition, Clinton's weakness on being honest and trustworthy could be an insurmountable problem for her in a hypothetical matchup against Bush. Plus, he has the advantage of getting an early Super PAC lead. That is going to go a long way in defining a candidate.
This might sound offhanded, however I believe the majority of the Hispanic voting base has been alienated by Donald Trump's comments and the Republican parties lack of punishment for him. If you were Hispanic, or Mexican, would you readily support the party who insulted your people. Doesn't seem logical to me.