Of course it would be a disaster for the entire world if Chinese-American relations were severed, but China does more than just create junk now. They have tons of natural resources, and have been expanding in Africa to increase their slice of the pie even further. They have a very flexible form of government, and while the immediate depression would be terrible, there's no reason they can't go full-nationalist/fascist and start building for themselves, as well as their immediate neighbors (the entirety of Southeast Asia seems to be going wonky right now). They're increasingly well-educated and could conceivably approach the cutting-edge of tech in a decade or two and be as competitive as any Western industry; a relative lack of ethical constraints could even put them ahead of us where medicine and biotech are concerned.
Oh, and they have nukes, which means most of the world is limited in terms of constraining their expansion.