No, actually the Republican leadership abandoned the grass roots. I know that it is somewhat semantics, but the leadership is the one that went off the reservation, not the rank and file of the Party.
As for those upset with Luntz for recognizing reality, I urge you not to be so upset - be happy, because the more that people recognize that the grass roots are sick and tired of the elites, the more likely it is that an insurgent candidate (Trump or Cruz) gets the nomination. The more that guys like Luntz say "this is about a done deal," the more likely that the GOPe will STFU and play ball. They WON'T like it, but they'll really have no choice.
They did that when they didn't support Goldwater.
Good riddance. I am done with them.