There are some near ready foundries in the US and in EU, not to mention South Korea. It would take a few years to catch up of course.
What I worry more about is the full lock-in of TSMC production capacity by nvidia/apple/amd/etc for their chips on their latest and greatest silicon process (aka the best in the world). There is 'no space' for performant large RISC-V implementations or other alternative (and it will require several iterations and mistakes will be made)
Tenstorrent managed to secure TSMC manufacturing capacity, I doubt many other RISC-centric fabless companies would have any issues aside from aggressive competition.
Im the EU there is Intel Ireland at least.
Interesting point, although it's clearly not in TSMC's interest to land themselves in a monopsony situation by allowing Apple (e.g.) to squeeze all their competitors out of the market.