This election, many Republicans won’t withhold their support from an openly cruel, sexist bigot. And there is a lesson in their failure. It suggests the best way forward. If the groups that Trump targets, especially the sizable ones, like women and Latinos, turn out in large enough numbers to vote against him, handing a crushing loss to the corrupting billionaire; if other folks who usually vote Republican join in that protest, to signal that this behavior is a dealbreaker; then the GOP will likely never nominate a man like this for high office ever again.