In 1980 50% of the US economy was manufacturing. It's 14% now. The transition to a service based economy was made, and we survived.
In theory the economic progression goes Hunter/Gatherer, Agriculture, Manufacturing, Service, and then Education based economy.
People making $50-60K/year turning a bolt probably need to look at their situation and think about other options, as that is not sustainable. They need to have a plan in case they are displaced. Call it a personal stop/loss.
When you invest you don't put all of your eggs in one basket, so why would people put their entire future in one basket?
The only jobs I know with near lifetime security is medical doctor or dentist or plastic surgeon for Michael Jackson.