Except that doesn't work either. If "sanctioning" a country was able to topple parties then North Korea wouldn't be an issue.
Not to mention that there are a whole slew of countries that wouldn't agree to any sanctions against China because it would hurt them just as much as it would hurt China.
Besides, a lot of those "problems" you listed are also present in western countries...
North Korea only survives because first the Soviet Union kept it alive and now China keeps it alive. China allows NK workers to work in China, and in turn they do business in NK. It is not isolated as you think it is.
On the other points: That is why you should never put all your production (eggs) into one country (basket).
Excuse but where else do you have a social credit system but China? Specifically western countries? What western country is a totalitarian single party ultranationalist pseudo communist state?
Aside from the fact that China's size would make it a lot easier to be self sufficient than North Korea, there are still plenty of countries that would trade with China, just like the USSR and China have done with North Korea, even if there were sanctions on China.
I'm not just talking about production. Plenty of countries benefit heavily from Chinese investment too. Removing that investment would damage those countries a lot as well.
While there may be no "western" country that shares all the problems that China has, some of those problems are still present. There's definitely some ultranationalism too. Plus the whole single party thing isn't necessarily a bad thing. Yes, you can certainly make a very strong argument that the Chinese communist party is a bad party to have in charge, but single party governments/dictatorships aren't inherently bad. Good dictatorships are better than bad democracies at least.
Besides, I'm sure there are plenty of "western" countries that have problems that China doesn't have. So why does China's set of problems warrant excluding it from the global community but the same isn't true of any other countries and their sets of problems?