The fam...

Two stories of North Korea's "royal" succession.
I consider this the most revealing story I have read in a while, yet it seems to me like most of it is second-hand, at best.

International Herald Tribune By Choe Sang-Hun, November 15, 2005
Kim Jong Il, the "Dear Leader" of North Korea, is pushing an age - 63 - when he is widely expected to designate a successor who will carry the mantle of power he inherited from his own father in the Communist world's first and only dynasty. But he has problems...

This one is very detailed, and most of it I have read in other accounts before. It did point out something I was not aware of, however...
The American Spectator By Patrick Devenny, November 15, 2005
The only other option for Kim Jong-Il would be his youngest, Kim Jong-Un. Currently 18 years old, his existence was only revealed to the rest of the world in 2001. Consequently, little is known about him, other than he is known by Kim as the "Morning Star King," and is apparently his father's favorite. His young age would complicate his rise to power immensely, due to the years of preparatory work needed to construct a powerful support system for the leadership candidate, such as the one that smoothed Kim Jong-Il's transition in 1994.
(H/T to Shoprat)

It's all nothing but wild speculation at this point. Hard facts out of North Korea are hard to find...