I'm not sure this is a plausible brink. The initial "tariff board" situation was 10 times more severe than this, and additionally this is a repeat of the same playbook.
This won't be the start of (further) major decoupling unless it's what China wanted in the first place, and they needed another 6 months of preparation before committing to the path. If China says "Go ahead and tariff us 100%. All rare earth exports and re-experts to the US are banned", then that's when to expect changes that won't be reversed any time soon. Everyone knows that Trump will blindly auto-escalate in response, so China saying so would mean "this is the outcome we prefer" and all that follows from there.
China has spent the last year(arguably the last decade) moving their supply chain to not rely on the US.
Trump is about to bail out a handful of US industries because of it. Specifically agriculture has taken tens of billions of dollars in losses because China entirely stopped importing US soy and other crops in the last year.
Trump's whole shtick is that the world NEEDS the US no matter what. He's absolutely wrong.
China has heavily invested in countries to avoid this exact situation.
This won't be the start of (further) major decoupling unless it's what China wanted in the first place, and they needed another 6 months of preparation before committing to the path. If China says "Go ahead and tariff us 100%. All rare earth exports and re-experts to the US are banned", then that's when to expect changes that won't be reversed any time soon. Everyone knows that Trump will blindly auto-escalate in response, so China saying so would mean "this is the outcome we prefer" and all that follows from there.