That would be just horrible. God willing Kim's regime will simply collapse of its own weight. Though if it does the people of North Korea may simply trade one tyrant for another, as China will move in.
I don't see it happening. National Geographic, Lisa Ling managed to get into NK a while ago with a eye surgeon. Seems they have more cataracts per capita than any nation -- probably because of their inadequate diet -- anyway, she said when the bandages were taken off the first thing these people wanted to do was see a picture of Dear Leader, and they cried when they could see him again. they are totally brainwashed because of lack of contact with the outside world.
Actually it would be the best (of many worse) options for China to "move in" preemptively: I.e. sponsor a coup against Kim and install a puppet government, a la Tibet.
Let the Chinese build North Korea back up to a mere dysfunctional sh*thole (as opposed to an utterly nonfunctional hellhole) and then 5 or 10 or 15 years down the line we can worry about pressuring the Chinese to back off and permit the reunification of North Korea with the democratic South.
It's not terrific, but I would be worlds better than what we're dealing with now.