By attacking McCain, I think Trump just stepped on a land mine. With a handful of exceptions, Republican Party apparatchiks, politicians, columnists, commentators and TV talking heads have been pulling their hair out over Trump's hijacking of the campaign.
And now "the Donald" has just invited the entire world to go nuclear against him. Already most of the other Republican candidates have attacked him. The only one to have publicly demurred was Ted Cruz, who is angling to inherit the crazy vote.
Adding to Trump's vulnerability is that, like other sons of multi-millionaires born in the first years of the post WWII baby boom, he dodged the draft during the Vietnam War first with a student deferment and then by buying himself a medically unfit draft status due to a supposed bone spur in one of his feet. This doctor-certified condition was so debilitating that Trump doesn't even remember which foot it was supposed to have affected.
McCain, on the other hand, volunteered for combat postings as a naval aviator, even though as the son and grandson of full (four star) admirals, the Navy's highest rank, we can assume if he had put in for some other assignment, the request would have been taken very seriously.
So here we have a New York loud-mouthed draft-dodging rich kid saying that the guy who volunteered to go and fight, who spent five and a half years as prisoner of war, who suffered especially harsh treatment because of his father's high rank in the military, and came out of the POW prison with permanent disabilities is a "loser" and "not a war hero."
I think the Republicans will have him so thoroughly roasted by tomorrow night that you can stick a fork in him and see that he is done. If they can't, it will be an unequivocal sign that the GOP is DOA for the 2016 presidential race. It will show that Trump is the albatross around the Republican's neck that seals their doom.
The Democrats will, of course, applaud (as faintly as possible) those Republicans who denounce Trump's insult against the national honor in general and McCain in particular. And some, I assume, will even be sincere about it.
But none of them are about to do the slightest bit of the heavy lifting, as they will be too busy preparing for the right moment to pounce on the Republicans as a whole for having tolerated and encouraged the outrage of Trump's campaign for all this time.