The outcome is inevitable. North Korea will cease to exist. It lacks the ability to sustain itself. How that end is reached has multible possibilities, but all require the cooperation of China, the United States, and South Korea. The extortion has to be ignored immediately. Accept as fact that the longer North Korea exists as an extortionist state the greater the potential damage from nuclear weapons as their development improves.
All three countries will need skin-in-the game. With an understanding, China must amass troops near the border with North Korea. This puts them in the position of facing strong armies on two fronts, an impossible position for North Korea. The best possibility is a total collapse without an all out conflagration. If North Korea fires missles, it would be attacked from both of its borders with significant loss of life, but a very short duration.
China would acquire some of North Korea for its efforts, and the rest would belong to South Korea. The US would withdraw its troops from South Korea. China, a communist country, is a stable world power with a rapidly developing free-market sector. South Korea and China would interact from a free-market perspective extremly well. The US could stop supporting an army it has kept in place for over six decades. People should keep in mind that Hong Kong, a free market, was returned to China and still operates as a free market. This Asian stability would be enduring and good for the entire world.