You've gotta separate cause and effect, especially when these things will change in the future. For instance decades ago I had family that worked in construction. They were earning about $20/hour in a rural area back when that was quite a lot of money, even in an urban area.

It was enough that, even with the on-off nature of the work (you're not getting paid when nothing's getting built), they could easily raise a large family very comfortably. Now a day construction in the US pays awfully and a big factor is the large number of illegal migrants working in it for sub-market wages. So you're talking about the necessity of solving a problem by expanding the thing that caused it.

It's very difficult to predict what demographic collapse will look like in a place like the US, but one general trend that might inform us is that fertility within places like the US remains strongly inversely correlated with income. Those who are earning a lot aren't having children, those who aren't earning much - are. Pair that alongside fairly low upward mobility, and again I think it's unlikely that significant numbers of unskilled workers will have any real value in the future (or present).