Imagine if all the FAANG companies (and equivalent) created a consortium and collectively funded the development of an American-made EUV machine and corresponding 5mm chip-production facility in order to compete with TSMC

Interesting though experiment. 

Do you we will view the decision to go fabless for many American chip companies as a mistake 5-10 years from now?

Eh, don't think any single company has the ability to build the full chip stack ($40bn+). Don't think it was a decision as much as their hand was forced