Most of the anger and hatred dissipates in the general election cycle. McCain wasn't well liked, and IIRC, Romney was more or less "hated" by most Freepers during the primary cycle.
There will always be some fraction of the electorate that refuses to support a nominee, for various reasons. I don't see either Cruz or Trump being more susceptible to that than Romney was.
I do agree with those who speculate that the party is working to knock out all of the candidates and substitute a person not currently running. I don't know if that has ever happened, at least before the era of the primary vote (first presidential primary was in the 1920's, coinciding with the rise of "democracy" and the demise of the republic).
Happy Blessed Easter to all! He is risen!!