It is impossible for Paul Ryan to be the nominee if the delegates vote to retain rule 40.
Any nominee or winner of the convention must have won 8 states in the most recent primary season.
Based on what I’ve read running Ryan will be next to impossible.
Rules are for little people.
But you just answered your own question, they’ll change whatever rules they want to change if they really decide this is worth using the nuclear option.
Will they? I don’t trust any of them not to. They may figure it’s better to try to retain control than to let Trump win and assuredly lose it.
Literally anyone can be the nominee, even under Rule 40. Because after the first ballot, the delegates can vote as they wish. If a majority in 8 or more states then switch to Ryan, he CAN be nominated under Rule 40.
That's my take on it anyway.
I guess a question then comes, can a rule be changed between ballots, say between 2 and 3? If there were enough delegates that would vote to change that rule at that point, I suspect some chaos might ensue.
Of course, this would also be electoral suicide. But if there are some things that the Republican establishment is not shy about if they see near term political or financial advantage, chaos and suicide would be right there on the list.