“Even if the rules were changed and Trump were thus nominated by less than a majority, Trump (or any candidate nominated through such a process) would be dead meat. A large enough share of the other candidates’ supporters would not vote for Trump in November”
You assume that most rank and file Republican voters understand the intricacies of Republican convention rules. They do not.
What they DO understand, is the simple concept of fair play and the idea that he who has the most marbles at the end of the game, wins.
If Trump has a sizable delegate lead going into the convention, most ordinary people are going to expect to see him nominated. If he isn’t, and the nomination is given to someone who didn’t win ‘most of the marbles’ fair and square with the people’s votes, it’s going to look like the rip-off of the century.
The Republican party will, for all intents and purposes, be dead at that point.
But those aren't the rules. This isn't marbles. Fair play, by the rules, is not based on what's popular.
Of course, you may be right in the sense that enough voters, whose "feelings" are that the nomination just has to go to the not-majority plurality winner, will be disappointed enough that we end up with Hillary. I already expect that at this point: the Cruz - Trump battle is so nasty that the wounds won't heal enough, whoever gets nominated.