This topic has been under discussion in our extended (mostly Christian conservative) family. And primarily regarding Kasich, for whom we who live in Ohio have voted for twice. The consensus is not that if Trump loses, civil war will "break out" amongst Republicans. No, we believe, to a man and woman, that conservatives will exit the republican party in droves. In other words, there will be only establishment types like Ryan left in what's left of the party. Why?
Because conservatives have had it with the moderate & liberal Repubs that the mainstream media loves. We are done with them. If liberal Hillary were to win, and able to pick the next 2 Supremes, what would be the point of remaining in this stupid party? Loyal opposition? BALONEY! We will leave - in droves.
One family member described Kasich as a big baby who is taking his ball and leaving, so to speak. Most of the rest of us think he is more calculating than that. We think that he has blinded himself to the reality of what is at stake with the Supreme Court. We are astonished that he appears to hope Trump loses so that he will have a chance at the big prize 4 or 8 years from now. If we are correct.... in his dreams. We would never consider voting for him OR Ted Cruz in future. I don't care at this point whether either of them back Trump, but neither of them will EVER get our votes (in 3 different states in my family) again. Period.