As other posters have said the economic dependence goes both ways. There is no sudden breakup scenario (i.e. a military conflict) that won’t be massively painful to everyone. I would note on the pain side for China they are significantly dependent on Western countries for coal (which runs many of their power plants, without which their factories don’t run), and they are dependent on other countries (not necessarily Western) for oil.
The next war is now and it is being fought in cyberspace. It’s a war of finding and exacerbating societal fault lines. In a generation, China won’t have to fight for territory such as Taiwan.
The Pentagon has been doing these studies for decades. The reliance on overseas suppliers has always been a concern. The US maintains “strategic reserves” of raw materials for just this reason.
Western nations could manufacture anything that is made in China, but the problem is time. It takes quite a while to build a factory and train the workers and work out the kinks to produce many manufactured goods. Never mind the cost.
It isn’t an either or problem-it is economics. When COVID hit, US factories geared up to produce lots more PPE. Great. China did too. Now the US firms are being driven out of the market by a flood of cheaper Chinese goods. It isn’t enough to have the ability to make something, a functioning supply chain and market is needed as well. That is a lot harder to maintain.