China isn't interested in immigration. In a relatively liberal and democratic country like the US, immigration is a boon because we don't care all that much about political or economic stability and are used to not having it. In an authoritarian oligarchy like China it's poison because an unstable environment will see the government in trouble quickly when people lose confidence in the party and leadership.

But if China starts importing immigrants, it will be just another shithole. Their quality and success come from their own population. Importing foreigners is just poisoning yourself your culture and future.