That is a good analogy, North Korea as China's Israel, it could potentially become reality. Since NK announced its desire to denuclearize under conditions of peace and a stable environment, I think there could be an arrangement where NK is under China's nuclear umbrella some time in the future. It is very unlikely NK would render itself totally vulnerable without nuclear second strike capability.
This is just a personal view but I think all along it was NK's grand strategy to negotiate a more equal international political footing with China before reform can happen. NK knows its only real backer is China, no other nation can possibly provide or willing to provide the road out but China has its own geopolitical views. China always viewed Korea as a vassal state, and NK is a rowdy vassal state, a trouble maker that needs to be tamed. NK knows how China views them, its nothing new, its very historical. This is clever political manoeuvring on NK's part where it became the focal point for China and USA, where it could play the two nations against each other. In the process of de-escalation they can extract benefits and boosts its international standing even if its a negative image, what matters are the interests at stake. Each side wants to use NK against the other, thus the two major powers are more willing to give major concessions to NK.
Ultimately NK wants to be on a more equal international standing with China. NK knows it cannot be a true equal but in the short span after a major international event, NK's importance would be highlighted, making China more willing to give major concessions to NK. China fears its international standing would be degraded if NK met with Trump first, thus China proactively sought out NK's visit. Especially concessions concering future trade and development. NK would likely take this opening to prepare for reforms and opening to China in addition to security guarantees much like ones the US provides to Israel before denuclearization could begin.
Had NK not played this big political stunt, NK's opening would render it just a minor vassal of China. The economic and political costs of nuclear program and ICBMs are the costs for negotiating better terms from China.
