Didn't the workforce drastically increase in the 20th century? I don't think it's hard to believe that as the number of people has grown, and the workforce has grown, the demand has also grown. (Demand being the want of goods/services) If people are able to get what they want with less employment, why does it matter that they can't find jobs? Maybe people will have more leisure time?
I don't understand why wages would plummet, but I'll accept it for the sake of argument. Maybe you're speaking in aggregates here, I don't know.
If you're speaking in aggregates, isn't it possible that people would work less hours and still find employment? Isn't it possible that less people in a family would have to work and still be able to provide? If people have more leisure time, there's no telling what they will actually do with it.
If you're speaking of wages of actually employed people dropping, then all this does is cause growth of inventories and a subsequent drop in the price of goods and services. Price deflation.
If people have a lot more free time on their hands at some point in the future, there's no telling what it is they'll do from looking at it today.