Re: A nuclear WWIII will never happen. Dishonor will prevent it.
A sensible observation, that there would be no honor in it, but I sense a few problems.
The first is that, to a military mind, voluntarily accepting defeat rather than using a weapon at your disposal is an even worse type of dishonor. You imagine that nuclear war involves a crass decision to launch them as an aggressive attack, Curtis LeMay fashion, and I agree that the considerations you discuss would preclude that.
But that raises the second problem, which is that nukes wait in the background of a separate escalation of "conventional" weapon use. I don't think Trump could persuade the military to attack North Korea with nukes pre-emptively, but he could probably attack with enough non-nuclear fire and fury that NK would consider it a matter of honor to use their nukes in retaliation, and away we go.
I read quite a bit of the Wiki article on the Cuban missile crisis, including the story of Vasili Arkhipov, one of the three commanding officers of a submarine armed with nukes. In response to an (almost accidental) attack with depth charges, they were (pre-)authorized to launch a nuclear strike. Arkhipov objected and thereby forestalled WWIII. The leaders had tickled the dragon's tail to an extent that permitted such an unplanned launch, and two of the three were willing to go ahead with the dishonor.
This part I have trouble taking seriously. If anything, it's an observation about why such a dishonorable first strike might happen. Our entire military is now geared up for "shock and awe" that might as well be an Xbox game. Cruise missiles, drone strikes, rocket launchers, heat seeking guided missiles. Not much sense of honor in all that. You note that face-to-face combat has been made impossible, but to my mind that means abstract decisions about faceless enemies are more likely to be abominable, not less.
If this is an argument that we don't need to try to pre-emptively take out North Korea's nukes, I would tend to agree. No matter how crazy the rulers are, I don't think they would start with a first strike or put themselves in danger of a situation which might call for one. I just wish I could count on the U.S. militarists not to flirt with such situations themselves.
Anything like an exit strategy for the U.S. looks like regime change, and we have shown ourselves willing to push awfully hard to try to put the leaders in an untenable position vis-a-vis patriotic supporters. So far, with very little effect. Yet the pressure of, on one hand, 45's "we have to do something" bluster, and on the other, the issues you raise such as nuclear winter, could result in a sideways path of least resistance toward a strategy of pressure on the regime. And I can imagine that resulting in conventional escalation.
Thanks, by the way, for getting into the ins and outs of the NK issue. It has been one of those things my mind tends to bounce off with a shudder, refusing to think things through to such an extent that I find myself accepting much of the propaganda line of the right.