China is surely not as dependent on the USA as the latter on the former. Even if the USA disappeared entirely one day, China would go on.
Never ever. The Chinese regime (state mafia) would collapse within a week and with them the whole society. They need a maximum of state terror even now, when the economy is booming.
They didn't collapse for a few millennia and now they would? China is still very underdeveloped country, so they would just get back where they started three decades ago. Not a long time really, taking into account the length of their history...
Yes, they are finished. Indebted already as grotesk as the globalized developed just-in-time-world, on which their economy is depending.