The US economy wouldn’t collapse without China, nor China without the US. They are so heavily intertwined economically that both countries avoid trouble with the other because the impact would be enormous.
China has manufacturing power. US has trade alliances and military power. Neither can overcome the other in simple terms.
If the US pulled out of China, the pressure on their allies to stop business with China would be the halting of sales of arms and support. Those F35’s require specific maintenance supplied by the US.
If China pulled out of the US, the pressure would be on US soil to bring prices of commodities down.
China is a cheap source of labor to the US, but so is India. Much of US tech support and manufacturing is moving to India anyhow because much of the educated population speaks English due to British colonialism. Over time, things would equalize and the new status quo would emerge. NEITHER country would cease to exist, and neither would acknowledge the growing pains.