Short of Clinton being hit by a meteor (and even then, I'm not 100% certain), Trump is done. He should have been done eons ago -- he should have been done from the moment he descended an escalator to announce his candidacy -- but he was already in polling freefall after the last debate, and after yesterday's horrow show, his position is utterly unrecoverable. Now it's merely a question of whether he remains in the race, or bails to save the last fragments of his public persona (and set himself up for a lucrative media empire catering to the lunatics who think that Fox News is too middle-of-the-road).
Thank goodness, but it's frightening how close he was. A couple weeks ago, he was neck-in-neck in the polls after an unprecedented period of a month in which he said merely appalling things. With a little discipline in the debate, and a few less skeletons in his closet, this goes down to the wire.
Now, if Trump had those qualities, perhaps he doesn't emerge from the Republican primary; being an undisciplined lunatic with a lifetime of odious statements was in effect his platform, after all. But he could have gotten it together for the debate and still have been just as dangerous in the Oval Office. He could have had this tape fall down the memory hole and still been just as horrifying a person. So thanks, Donald; if you were half as clever as you believe yourself to be, your sociopathic behind might be a coin flip for president.