I think it HAS changed...that's why we are seeing outsiders polling at 65-70 percent. It isn't so much about political ideology, something else is happening. That's a huge cohort - the party appears very united, but against what it sees as the establishment and the politics of the past.
The Republican Party is NOT:
In favor of banning Muslims
In favor of shipping 11 million illegals over the border to......somewhere...in boxcars
In favor of eminent domain
In favor of single payer healthcare
In favor of letting Russia handle ISIS
In favor of imposing the death penalty on states from the Oval Office
In favor of taxing corporate profits held overseas at 20%
In favor of ridiculing handicapped people in public
In favor of commenting on menstrual emanations of journalists
In favor of ridiculing the facial appearance of its female presidential candidates
In favor of celebrity populism
The Republican Party is far from united. And Trump will not unite the party if he is nominated.
Which means he will lose.