Taiwan, and Asian semi ecosystem at large is unique, and irreplaceable, and not only TSMC as such.
The fall of Taiwan will be:
1. Loss of unique, black box knowhow which people never put into any patents
2. Loss of single source consumables - a lot of chemical industry, metallurgy, plastic, machinery all exclusively used only by semi industry
3. Loss of 80% of world's semi workforce, both brains, and hands
4. Loss of services companies, and big part of the ecosystem supporting the fabs, like semiconductor logistics
5. Loss of unique semi equipment makers, not on the level of losing the crown jewel (steppers,) but nevertheless making it instantly impossible to build any new fab line until a replacement is redeveloped from scratch. People who say that Taiwan is not big in semi tool making don't have an idea.
So if you completely erase this part of the world, the maximum the world can hope for within 5 years is just to restore functioning of a single pre-existing fab per country.
All its outputs will be no doubt be only used for defence electronics.
In other words Facebook, Amazon, Google, and all tech industry all bye bye. Modern "disposable electronics" barely lasts 2-3 years.
South Korea, or Japan will be there first, and they will demand The King's Ransom for fab access.
The first new fabs built from scratch will only be possible to make in 7-9 years term, using eighties era technology, and that is if the war will end quickly.