I agree with everything you wrote, but I’d also add that the period of globalized megacoporations became inpactful in the 70’s, and robotic automation started to become impactful in the late 60’s.
Both have had the effect of eroding working class wage opportunities; ergo, when you’re looking at the income inequality increase over the period, there are two variables at play. The first is the one everyone talks about politically, which is that more and more of the profits went to the upper class; however, the job erosion of the middle class also contributed substantially to the overall effect.
And, if you like THAT, wait until self-driving trucks destroy one of the remaining occupations where a person without a college degree can earn a middle class living. :-(