"One factor to consider here is what happens if no conflict occurs?"
Another angle is the threat North Korea wields is not static. 20 years ago we were worried "What if NK starts shelling Seoul?" Now we're worried "What if NK nukes Seoul or maybe Japan?" We're either at or just a year or two away from "What if NK nukes Hawaii?" with rapid progress towards "What if NK nukes the United States?" Give it another twenty years and it'll be "What if NK launches all of its couple hundred nukes at once?" and "What if NK deploys its bioweapons?" or even "What if NK simply accidentally mishandles its bioweapons and something it is developing gets out into the world?"
I'm not advocating for any particular solution here, not least of which is because at least at the moment I haven't got any skin in this game... at least, for another year or two, until NK can indeed reach me with a nuke-tipped missile, and even then, the odds they'd pick where I live is very, very low.[1] I don't know exactly how to analyze this case in game theory. But I at least recognize there is an element of this setup where even though at any given moment the locally rational thing to do is not to attack or provoke North Korea, the globally rational thing to do is probably not to keep choosing that choice indefinitely. One way or another, eventually North Korea is going to have to offer the international community another choice, whether it likes it or not.
(My personal suspicion is that China really is moving to constrain them and we see a good chance of perhaps-surprising cooperation, even if a Kabuki show is put on about the details, because it was all fun and games for China when what NK has was artillery pointed at a foreign city they didn't much care about, or had some scary weapons pointed at them. Even a couple of small nukes that can't reach China's really important assets might not concern them. But unless North Korea's posture has 100% been a carefully calculated act by otherwise ruthlessly logical individuals, which I'd suggest is not where the evidence points us, an actual nuclear power North Korea that has dozens of missiles that can reach anywhere in the world becomes a true threat to China as well, not only directly, but in that it might give other regional powers Ideas about how to "more effectively" leverage their nuclear arsenals to extract concessions from China, which I'd expect NK to immediately move to do as their only refuge at this point would be in audacity. As the NK threat continues to ramp up they become a threat to even more actors. Even for the US, the NK has been more "thorn in our side" than actual threat.)
[1]: Though that probably doesn't apply to all readers here. If I were North Korea and I was looking for ways to hurt the US, Washington DC would be my target #1... but Silicon Valley would be on my very, very short list, as not only hurting the US financially, but also symbolically. Personally I think I'd put Hollywood above it, then maybe New York, but Silicon Valley makes a pretty plausible 4th, as a way of striking the industry where the US is arguably most clearly leading the world in one relatively small place. So, you know, this discussion is IMHO getting rapidly less theoretical than some of us may like.