What do you mean? Kim il Sung is the eternal leader of North Korea. Kim Jong Un is merely the figurehead for his dead grandfather.

Speaking to a US academic while I was in Viet Nam last week, economic analysts reckon that a unified Korea would, within a relatively short space of time, become the biggest economy in Asia. And clearly a unified Korea would be one that brings North Korea into the South Korean fold, much like East Germany came into the West German fold. Clearly China has a great interest in seeing that not happen. Just as China is set to become the new world power, stepping over the USA in the not too distant future, they do not want to see a western aligned neighbour rapidly rise to rival them in power and influence. Apparently North Korea is pretty resource rich, it just lacks the investment and technological capability to extract them. In that respect China might be keeping North Koreas recources aside for a rainy day. Much better to roll in to North Korea with economic aid and infratructure investment to exclusively get to those resources and consolodate power as and when China needs it, than to release those resources on the global market to benefit others and especially South korea and the West.

It makes a great deal of sense to keep a neighbour with untapped potential down and isolated from the world so that your own strategic position can be maintained and, when the time is right, increased through the exploitation of that neighbour's untapped potential.

This dude:

Actually he does 2 or 3 I think as his father Kim jeong il had more sons than just him. In fact Kim jong un is the second son and he was picked over the first son to rule.

It's like any absolute monarchy so probably his wife or an uncle. Although, hopefully people would use that as a good time to rebel and demand better. Their ideals failed and they must acknowledge it. Think how difficult it would be to re-educate these people. Unification would probably bankrupt south Korea.

They would democratically vote in the next person.

it's not that easy tho.

South korean people have to agree, and I believe they hate eachother because of years of propaganda.

Also the economy of the north is way worse and totally different than that of the south. 

So to make 1 Korea the south will need to invest a lot in the north, and I can understand them that they don't want to do it or do it alone.

The best way to do this is for the international community to chip in on north korea, build an infrastructure, grow the economy and give them their own governement. And maybe after a couple of decades there is a chance Korea will be united once again. But the north will still be poorer than the south.
eastern germany still has a lower average capita per head then west germany.

Were messing where we have a chance. Not where we none.

Mecha Kim-Jong-Un