the world would follow in a heartbeat

I doubt that very much. Even countries that don't like the US much buy US debt, and not so they can join some mass movement to destroy the US. Nobody likes China all that much, either. If China started dumping, then other people have to be buying. You can't sell something people don't want to buy. So China has to ask a much lower price to sell their US debt. Rich people and other countries buy $100 worth of bonds for $90. Once China is out of bonds to sell, the price goes back up to $100, because US debt is backed by the ability of the US government to collect taxes. China just gave 10% of it's US debt investment to everybody who bought those bonds. China is poorer and the buyers are richer.

US bonds have an intrinsic value floor because they pay competitive interest. Even if the price drops, owners don't have to sell and can keep on collecting that interest. Damaging the US by dumping their debt is not something China can do. Some moron demagogue like Trump could do it by refusing to honor US interest obligations, but that's not up to China.

We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.