Does China still want Taiwan if it's no longer technologically relevant? My understanding is that China is making similar strides in its own chip industry to the point where TSMC won't be as nearly as useful to them in 10 years as it is now.
Anyhow, the U.S. has no need nor desire to establish a presence on Taiwan. Okinawa and Korea are more than close enough for its purposes, peaceful or otherwise. And if the U.S. were to try to establish a presence, you can be sure China's invasion fleet would reach Taiwan before any significant U.S. materiel could make it ashore.
In fact, when taking apart China-made, China-designed products, I am frequently very impressed at cost-cutting measures that are taken with minimal impact on the functionality of the product.
If Taiwan stopped making those tools you would be impacted. The world overall... not so much.
TSMC’s revenue is less than a tenth of Taiwan’s total export revenue. They might be the most profitable of Taiwan’s companies, but Taiwan has a huge economy.
And it terms of impact on the world economy, Hon Hai precision, better known in the west as Foxconn, would like to say hi.
In fact, I wouldn't be surprised if making Taiwan globally less economically relevant is core to their strategy for reunification. While the US is dependent on Taiwan for chips, Taiwan has a very important defense partner that China can't really compete with. But China has a way better chance of securing Taiwan if the rest of the global community only cares for ideological reasons.