Let's concede the obvious first : a confrontation between the USA and North Korea have a very obvious outcome. That outcome also involve grievous costs for the US.
That said, what are the chances that the North Korean nomenklatura accepts, even during duress, to underdo a regime change ? (I don't think I'm stretching the truth much by suggesting that threatening the regime presumably come with hopes of convincing moderates that the Komrade is a bad horse). After all, Eastern Europe saw the previous nomenklatura switch rather easily to capitalism...
It's going to be much harder to implement in North Korea, alas, for a simple reason : the North Korean elite is more and more aware already that there is a gap between the life standards of even an unskilled South Korean worker and a North Korean. They are not going to turn against the Kims for material goods, because the said elite is also perfectly aware that South Koreans are going to devour them alive.
After all, a Eastern German in 1990 did not had relatively useless skills in technology, management, information, and the like. There was a gap between East and West Germany, but a matter of years, not decades. If you are a North Korean factory manager, what are the chances that you can remotely compete against someone from the South ? (If only because in the South, the factory actually products stuff, while most North Korean industry have bouts of inactivity).
To take a biblical metaphor, the average North Korean bureaucrat is not going to support regime change from a bowl of lentils. Not because of communist conviction, but because they known damn well that they will be at the bottom rung of the society if they are not shot (FTR, the economic privileges of the North Korean elite are apparently quite modest-a North Korean ''fat cat'' does not live much better than a Western blue collar worker ...)