That'll be interesting, except it's too late to do anything like that. Trump is the nominee. Voting's been going on since September. It's way too late for them to change their nominee. If they want Pence (who would be a totally different disaster than Trump), they'd have to convince people to vote for Trump and promise to remove him the second he's inaugurated (there's already enough to actually IMPEACH him), but that's not going to give anyone any confidence. "Vote for us, we screwed up but you can trust us to handle it!" Yeah, right.
A lot of the people who are psyched to vote for Trump are doing so because he's not a politician. If Trump drops out, they won't pick the Republican replacement, they'll just stay home. That's a big chunk gone. A lot of Republicans are saying they'll write in a name, but I don't know if write-ins for Pence would count the same as votes for the Republican nominee (and who's to say they won't write in someone else's name?)
There's never been anything like this in American politics. It's kind of amazing to watch. I wonder what the end result will be, not the election results, but the future of the Republican and Democrat parties, how nominees are selected... a lot has to change, but I doubt that anyone will ever actually learn from their mistakes. They'll chalk it up to an insane black swan moment and subject us to more of the poor planning, crummy news coverage etc that we just went through. We'll never have another Trump, but I sincerely doubt the system that let him in is going anywhere.