Now Trump has given the conventional wisdom something to double down on the whole idea with. Example, from Peter Beinart at The Atlantic:
At times during tonight's debate, Donald Trump seemed controlled, succinct, even prepared.
It didn't matter. In an instant, he lost the debate and blew his chance of using it to turn around his sinking campaign.
That instant came when Trump refused to say he would respect the outcome of next month's vote.
Beinart offers all kinds of reasons why that answer, especially if it becomes "the new normal," would be devastating to the system of rule commonly referred to as "American democracy." Then he claims again:
The good news is that Trump's answer will devastate him politically -- perhaps even more than the groping scandals. It will devastate him because the minute the debate ends, journalists will begin asking every Republican they can find whether they agree that he doesn't need to concede defeat. And many of those Republicans -- including the ones on Trump's own campaign -- will feed him to the wolves.
If I had a nickel for every time Republicans tried to feed Trump to the wolves and it turned out that he was just too tough to bleed from the bites, I'd have quite a few nickels.
Trump's base is composed of people who have believed for a long time that the whole game is rigged by e.g. "the liberal media," and who are glad to hear Trump saying out loud on a real stage what they've been thinking and muttering among themselves for years, and who will not only not abandon him but are even more likely to get off their asses and go vote in November because they heard him say it last night. They want a candidate who will refuse to concede a defeat they don't believe he can legitimately suffer.
I will be reconsidering my presidential election prediction (that Trump will carry every state Mitt Romney carried in 2012, plus Michigan, Ohio, Pennsylvania and Florida) and modifying or confirming that prediction some time between now and Election Day. Part of my model is this: I predict Trump to win pretty much any and every state where he is polling within 5 points of Clinton when I finalize my prediction. His voters are more motivated to actually turn out, but many of them are less motivated to admit, even to pollsters, that he's their guy.