It seems plausible to me that growing markets like India could fill that hole over time, yeah.

The “over time” is doing a lot of heavy lifting here. It won’t happen on anything remotely resembling a time horizon that matters for these purposes. Factories will be closed and gone by then.

If the US buys less, there will be unsold inventory and a temporary glut in supply, which will lead to the Chinese dropping prices and exporting elsewhere. This is already happening in SE Asia:

https://www.chiangraitimes.com/china/china-export-dumping/

Obviously the profit margin will be less than selling to the US, but it does mean that the 3% of GDP mentioned above is not going away entirely, just shrinking to (say) 2 or 2.5%.

The article also mentions transshipment, where Chinese goods get routed to the US via a third country. Although Trump's strategy of "tariff everybody for all the things" is putting a damper on this too.

When demand is reduced, you lower prices. Rest of the world suddenly are buyers. Governments can throw subsidies at impacted sectors too to cover the price difference while supply chains adjust. With growing trade relations, economies of scale and transition costs become factors. The cost of trade with the new trade relationships become cheaper and so does the reluctance to change (for example with a 3 year production pipeline baked, you don't walk away easily).

As an example, I'm pretty sure I just took up some of the slack here in NZ. I've been looking at installing solar for a while, and a particularly good quote for a Chinese system (Sigen) recently made me go ahead. I strongly suspect the unusually good price and fast delivery were due to cancelled US demand.

OT: Solar is awesome! 18 panels are generating 2/3 of our load, despite it being late winter. And a 16kWh battery means the grid power we import is all off-peak. In summer we're going to be exporting enough that we may even cover our winter grid import. Plus it gives us the best UPS system we've ever had, including zero-second cut-over (c.f. Tesla's half-second glitch).

> OT: Solar is awesome!

Don’t tell that to the Americans, they hate renewables now.

China exported something like 525 billion worth of goods last year to the US. Not all good can be replaced but let’s say something like 350 billion worth of goods are unmarketable because of the tariffs. Do you really think the whole world can’t swallow 350 billion of imports?

You’re ignoring the fact that the demand and supply were in equilibrium before.

So the world needs to absorb almost half a trillion of new supply.