“If there’s one thing history has proven, it is that maniacal dictators don’t like to die alone. “
Therefore the strategy of taking out the nuke capability and leaving his conventional forces intact.
Leave his security blanket and borders intact.
Even China would not act against that strategy.
That said, you make a very good point. Such a strategy would save face for both the Norks and Chinese, such being vital to their way of thinking.
Some conventional Nork assets would still have to be removed, that is, those pointed at Seoul with standing orders to attack at any breakout of hostilities. Figuring out what those would be is likely problematic, so we will inevitably miss some, meaning Seoul is going to take some damage, no matter what we do.
War is like that, unfortunately...