Zero chance the GOP delegations fail to vote for the GOP nominee...they'll know that if they split at all Hillary will win. So the chance of Trump not winning a House election at that point would be zero. Not a longshot. Zero, because there is no chance of flipping 26 state delegations to some unknown pupped of Bill Kristol...who likely is a perfectly nice guy, but a puppet nonetheless. Its absurd, and I think you know that.
Hillary needs a majority of the delegates within the delegation to have it (ie. the state) go for her correct? Not just a plurality.
In other words:
California has 53 reps.
If HIllary gets 26 reps, Trump gets 13, and French gets 14 she does not win that state, no matter what. She would need 27 "delegates" to win that state delegation.
Therfore vote-splitting doesn't apply. Vote-splitting only applies in plurality situations. GOP primary was an excellent example. Had it been 100% proportional, Trump would be staring at a contest convention.