The TSMC fab in Taiwan is the world's most advanced. There are no other sources for 7nm manufacturing at the moment. Moreover chip designs can't just be immediately re-spun onto older processes: if it were lost to China then basically the rest of the world would completely lose access to a fresh supply of the best chips. Tech would immediately have to roll back a generation of two, hardware wise, and of course software that relied on that performance would also need to roll back, etc.

Finally, programmers would have to actually optimize :D

Various DRM-like schemes can be used to make a chip useless without the software that goes with it.

If TSMC was concerned about the US taking over their factory, they could design lots of elements of the process to require a connection to HQ in Taiwan, and to stop working when that connection is broken.

When every piece of equipment has no working firmware, the factory is pretty much useless, and would probably take years to get running again.

No TSMC plants exist in America right now.

Actually, TSMC has operated a fab in Camas, Washington for many years.

Oh, interesting! Thanks for the correction.

Note that the wafertech/TSMC fab11 only does processes down to 0.16 um.

https://www.wafertech.com/en/foundry/technology.html

I'm not really following the logic... GP said this (TSMC intending to build a factory in US) was bad for US, because China could march into Taiwan and cut off US ability to make chips.

Wouldn't a TSMC plant in US be good? Since US would have the factory on its own soil? What am I missing?

My understanding of the GP is that the current situation with TSMC only in Taiwan is a disaster. So I think they are actually in agreement with you and I that this is (or could be) a good thing.

Ah, got it. I mis-parsed the comment.