Just thinking out loud, all call it daydreaming...But, what if he's dead and there's a large internal power struggle over his successor, and China gets involved...and they, by some act of miracle, allow South Korea to absorb the North and reunify the country. Wouldn't that be a huge gift to the world? Again, I know I'm dreaming, but it would be nice if it could possibly happen.
Aside from being incredibly unlikely, it probably wouldn't be a good thing anyway. It would just screw over South Korea. Firstly the economic gap is absolutely massive. The economic difference between west and east Germany caused some issues after they reunified, but the difference between the Koreas is much larger than that. Then there's the issue where the north Korean populace have effectively been indoctrinated into believing they're the best and the Kims are fantastic and ever foreigner is an enemy for their entire lives. That would surely cause a whole bunch of issues too. If a reunification is to happen it would need to be done slowly, probably over a decade or two, in order to minimise the issues it would cause.
Besides, if China intervened and stopped North Korea from being an independent country it would probably be because they made it a province of China, rather than it reunified with the south.