It's completely "self-evident" to me that the US can never re-achieve post-WWII prosperity largely for the reasons OP stated.

It was a moment in history that will not repeated in any of our lifetimes. Anything else against this backdrop is basically a rounding error.

I was alive during the drawdown of US industrial capacity and my entire family was blue collar mostly union workers. In my teens and 20's I worked such jobs. This narrative still rings largely true to me. The amount of outright waste and fraud in these industries at the labor level was astronomical. We were begging to be outcompeted. Combined with managerial incompetence we were doomed.