Re: It won't be just minimum wage jobs
"the same workshop had at most 10 people left on the main shift with perhaps a couple at night. "
A lot of places that only used to run in the daytime started loading up the CNCs with repetitive jobs for overnight work. One customer of mine branched out into making towballs this way and it became one of his main money earners within a year - enough to pay for a bunch more CNCs
"In those days we tried to retrain people or paid for them to retire early"
And this is where the whammy comes along for millennials. In times gone by, employment would be largely driven by the rate of retirement of the existing workforce (which is why after WW2, thanks to "enlightened social planning", the retirement age was made mandatory in many countries, to ensure there were jobs available for Boomers). Nowadays it's common across the board for a retiring body to be replaced with expanded automation rather than a new apprentice.
There are exceptions of course. Electricians and plumbers aren't going away anytime soon, especially for retrofit jobs but the constant pressure to decrease costs is hard to resist when labour is the predominant item on the invoice these days.