Having worked in Fab, the supply chain is already in the US+EU+Japan. About the only change in last 5 years or so is Intel's ability to compete in lithography process and get sufficient yield to stay competitive in pricing. Lithography is one of the 400 or so steps in Fab processing, but arguably the most critical and a bottle neck. TSMC does not have a lead in every single of these 400 steps, in fact quite the opposite.
Anytime someone says "impossible", I would take that opinion with a grain of salt.
According to US Semiconductor Association's recent State of the Industry Report, Taiwan's share in the manufacturing equipment part of the supply chain is almost nil and entirely depends on suppliers in the US, Japan and EU.
I guess Apple's decision to leave Samsung's Austin fab back in early 2010's to TSMC in Taiwan had an outsized role in TSMC's lead in tech and rise in revenue -- Apple accounts for 25% of TSMC sales.
> Anytime someone says "impossible", I would take that opinion with a grain of salt.
Or to quote Arthur C Clarke:
> When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
Anytime someone says "impossible", I would take that opinion with a grain of salt.