Welp lets consider two facts here:
1) In about 50 years whites in the country will be a minority.
2) New immigrants are extremely unlikely to vote for anything other than liberals and socialists
Do you disagree with either of those two statements?
Point 1: What does it matter? Why are you concerned about that?
Point 2: You'd be surprised how many people like the conservative economic message. What drives people away is screeching that, because of their religion, race, ethnicity, sexual orientation... that the GOP hates you and sees you as less of a person.
Cases in point:
Asian voters used to be predominately Republican voters. Not anymore.
Cuban voters used to be predominately Republican voters. Now it's about 60% Democrat.
Black voters used to be equally distributed between the parties. Not anymore.
Hispanic (non-Cuban) voters were, at one point, voting at nearly 40% for Republicans. Not anymore.
College educated white Americans used to vote mostly for the GOP. Not anymore.
How any times must a party lose growing constituent groups before they realize that demonizing anyone not a lily-white WASP is a losing proposition?