Excellent analysis of the Korean situation! I really enjoyed reading it.
Having lived in the Soviet Union just before it fall apart, I have some first hand experience of PHRASECENSOREDPOSTERSHOULDKNOWBETTER. regimes.
When my family left in 1988, there already was quite a bit of dissent: we openly talked about shortages and deficiencies amongst our friends, there were concerts of "forbidden" rock-bands, overall there was a general "westerly wind" in the country.
There have been only individual defections of North Korean soldiers to the South. Even small, unit-level defections—which would indicate that soldiers are talking to one another and are no longer afraid of exposure by comrades—have not yet occurred.
This indicates to me that Korea will not collapse by itself any time soon. Kim Jong Il resembles Stalin and his Gulag, much more then he resembles Gorbachev and his Perestroika.