I remember a very old WSJ article about "swiss style machinists" and how there are no young American ones any more. This style of machinist makes tiny objects (think of how small things inside a mechanical watch are), where a day's production fits into a coffee cup. It takes a 10 year long apprenticeship to become productive enough that a company is willing to one of these machinists. All of the "younger" ones came from Germany or Austria because their governments subsidize the long training & apprenticeship programs. In the US, virtually all of them were laid off at the end of the Cold War.
Like most trade workers, the worker owns the tools that they use on the job. When they sell their tools, they leave the trade.
I don't think there have been any good studies or histories written about the decline in tradeskilled labor.
There's a lot of discussion about how tradespeople are retiring and leaving big gaps in the workforce, and there's a strong element of truth to it, but America is still producing large and small machined parts.
There's still large machine tools being refurbished in Rockford, Illinois, Haas is building a large new facility in Nevada (delayed; thanks covid) for making CNC machine tools, medical and aerospace parts are still earning machinists a crapton of money, and people are still hobbing enormous gears that are very, very expensive.
It's pretty clear that American machining has lost its production bandwidth due to offshoring, but it's not accurate to say that the field is dead.
Like most trade workers, the worker owns the tools that they use on the job. When they sell their tools, they leave the trade.
I don't think there have been any good studies or histories written about the decline in tradeskilled labor.