The OP glossed over this part I bolded and I don’t think it’s gotten enough attention since.
The working world isn’t split between knowledge workers and manufacturing workers. It’s actually tripartite, with service workers as a third leg.
Service traditionally was lower class, as in households servants. The original industrial revolution gave a non-farm alternative to service, by introducing large number of factory jobs. By the beginning of WWI, house servants - once present in almost every middle-class household - had almost vanished except for the homes of the rich. Many of these positions, especially those held by women, didn’t go over to manufacturing, but to the new service jobs catering to the middle class. These were predominantly clerks in the new department stores and other retail establishments, but also telephone operators, receptionists, waitresses and other business that became traditionally female-oriented jobs.
Jobs perceived as being female almost always got less pay, less job security, less chance of advancement, less in the way of health and pension benefits, because they were seen as second jobs, therefore not as essential to the household.
The recent loss of manufacturing jobs doesn’t reflect a switchover to knowledge-based positions, but a combination of knowledge-based and service-based jobs. That’s where the concerns about American jobs comes from.
Until after WWII, no more than about 5% of the U.S. population went to college. Knowledge-based jobs were premium and paid well, because the pool of applicants was small and well-qualified. Today about 50% of the U.S. population goes to college. The number of jobs requiring a college degree has grown, but the proportion of them which truly require advanced education remains small. For the rest, a college degree is an artificial barrier.
That puts both the middle and lower sectors of the population in a bind. There are fewer manufacturing jobs for the semi-skilled worker, and therefore fewer opportunities to join the middle class. There are fewer laboring job for the lower classes. Neither can complete for the professional-level jobs. Where do they go but into the expanded service industry? But that merely increases the pool of applicants - greatly expands the male pool of applicants - for jobs that still receive less pay, less job security, less chance of advancement, and less in the way of health and pension benefits.
Most people are not really suited for knowledge-based jobs. But the spectrum of the remaining jobs has changed, as least for now, for the worse in terms of pay and prestige.
Since 1966 many people have recognized that it’s the problems of a service-based economy that the U.S. is suffering, partly because so much emphasis was placed on achieving a knowledge-based economy that was wholly unreasonable. I have to ask the OP where these articles about transitioning to a knowledge-based economy are coming from. That’s so last century.
The real issues are improving jobs in the service-based economy so that even two-income families don’t fall out of the middle class.
That has no factual answers, of course, so anything further belongs in GD.