The same way the US has a permanent interest in the continued existence of an independent, non Russian Federation aligned Crimea. If Taiwan looses it's economi

The same way the US has a permanent interest in the continued existence of an independent, non Russian Federation aligned Crimea. If Taiwan looses it's economic value (say, chip production becomes a commodity when Moore's law truly ends, and the CCP subsidizes local chip production to kill off TSMC), it may not be worth the nuclear war to the CCP 'no'.