I agree that the times when the GOP could count on holding the field by mostly just appealing to the whites and guarding "white interests" (Middle America, white corporate America, Trump America, whatever you'd call it), those times are coming to an end. In the future they are not going to be able to do that kind of Reagan/Rove thing if they want to win the White House or a solid Senate majority. "It's the demography, s****d" - and some of them are recognizing it. Carly Fiorina essentially owned up to this in some comments she made after the 2008 election, after she had broken with the McCain/Schmidt team. But I doubt that will make them revise their actual politics in depth or make for an effort to build bridges to let's say black and hispanic groups who are demanding social justice, a new immigration policy, a major rise in minimum wages and so on. That would be, well, a "new deal" within the republican party and its sponsors.
Plus, the core of the GOP and the tea party people would get very unpredictable and angry at such a move. That's part of what makes the Trayvon Martin case so foreboding.