I think you may be underestimating both NK and Kim Jong-un. The fact that the Ryugyong hotel is going to be completed after a 25-year freeze is a significant marker that seems to be overlooked. I think the new NK Leader understand better than the older generation that military development cannot keep pace without economic development as well.
Well there has been relatively little movement in any field since the new Kim took over other than some purges. Unless I see real significant change, I see no reason to review by assessment of the Kims or NK.
What if the SK-USA alliance reaches military technology that renders NK military largely obsolete, including their trump card, the A-bomb? What if China reaches a powerful enough military where they can easily overrun NK?
I don't think it's a question of 'what ifs', the SK-USA alliance already has the military and technological edge it needs to neutralize the NK military, even it's nukes to a certain extent. The biggest factors staying their hand is the fact that ABM is far from 100% effective, so there is still an unacceptably high chance of the odd nuclear tipped SR/IRBM slipping through and glassing millions of people; the geographical location of NK, with NK artillery and missiles easily within range of large sways of Seoul and other urban centers, so any war will see those areas reduced to rubble with catastrophic civilian casualties; and of course, the 'big one' of China's support for NK, and the possibility that the PLA will directly enter the war as it had done before, in which case a relatively easy military victory for the SK-USA alliance could turn into another grinding war of attrition and stalemate.
Now, even if you take away China's support, I don't think SK or the US will ever launch an attack on NK because of the damage it can do to SK and the civilian casualties it can cause before they are obliterated. In effect, NK is like a madman with a gun held to the head of a hostage (SK civilians) and wearing a suicide belt (nukes).
Everyone knows he is a problem, but since no-one knows how to disarm him without him killing the hostage and/or blowing himself and everything around him up, the world kinda just tries to pretend he isn't there and throws him some scraps when he gets too agitated.
Because of all this, I don't think you be actively plan to launch a war to topple the NK regime, and what I have suggested would only ever realistically work as a contingency plan.
However, the limitation to NK's strategy is that he can only kill the hostage once. If by accident or design the preverbal hits the fan and NK artillery does flatten downtown Seoul, SK and the world needs to respond nukes or no nukes, and since SK has already taken such a heavy hit, there is very little stopping them from going all the way.
If such a day ever comes, I think that it would be in everyone's best interest (other than Kim's of course) if Beijing just gave SK a grant bargain. The PLA 38th army is going into NK followed by massive reinforcements, there is no stopping that, the only choice SK has to make is whether the PLA does that as it's allies or enemies.
Faced with such a choice, and if China can keep it's demands reasonable (like no US bases anywhere on the unified Korea, greater economic integration in exchange for Chinese aid etc), there is a very good chance SK will agree. This is another reason why the SK-US alliance will never unify Korea - the US would not want that since a unified Korea would not really need US support anywhere as much as it does now.
In order for the Kim dynasty to survive, economic reform is a must. However, economic development necessarily means an end to isolation, which would have a profound impact on NK society. I believe that NK is right now in the same stage as China at the end of the Cultural Revolution.
Well it's like catch 22 for NK. In order to allow economic development, they need to loosen their grip on power and information and that does not look like anything they are prepared to do, because there is every chance that loosening it's stranglehold on power and information will lead to the collapse of the regime from internal dissent long before they see the economic fruits of doing so.
Chinese economic reform only worked because China established special economic zones and threw out dogma and control in exchange for efficiency and innovation.
NK has thus far resolutely refused to follow China's model, despite urgings and pressure from Beijing, precisely because it dreads any loss of control. I do not see that changing, and so long as that does not change, there will not be a real economic revolution big enough to change NK's trajectory and fate.
