Right you are, in a fair world. But I see a way the GOPe can steal this thing.
Suppose Trump has a bare majority of the delegates (say, 51%). Then the GOPe changes the rules a bit to allow for "superdelegates", just like the Democrats do. All of a sudden Trump's 51% becomes, say, 48%.
The GOPe folks could then offer deals to the other candidates to get them to band together against Trump. In this unpleasant scenario, anyone could end up with the nomination, even Jeb.
I hope the GOP tries this.
Repubs do have over 400 unpledged automatic delegates: GOP office-holders and state RNC members.