I remember back then the assembly labor cost of a $400 iPhone is about $120, with Foxconn charging 6% profit margin. Let's say today it is $150 labor cost in China due to inflation, at $5/hr. US labor let's say is $24/hr, this $150 labor will become x5 and $450, so that $400 iPhone will have to sell for $900?
I think most likely they will move to somewhere else or be completely automated, so maybe 1 US worker feeding the robot to replace 5 Chinese labor, or more likely, someone will build a factory full of robot in, I don't know, Poland or India?
US never exited the semiconductor industry. We have fabs from Intel that were mismanaged but in good volume. Had they not hired a few accountant CEOs they would not be where they are today. Micron is doing well and not have cost disadvantage compare to Kioxia or Samsung / Hynix due to US labor cost. Heck, Boise ID probably have lower cost than Seoul anyways.
The problem with US semiconductor industry is always the accountant CEOs not wanting to invest, they don't want to pump in $20B to make 30% profit margin when foreign government want to win at all cost and guarantee $20B of loans to make sure the risk is minimal.