Economies of scale was a part of the old industrial system, like big cities.
Today, with CAD/CAM and rapid prototyping what is available are products as individualized as under the old craftsman system at industrialized prices.
Your thesis is perfect for the last millennium.
So9
Maybe.
I've always thought the perfect population mix following a global calamity would be me and the Hooters girls volleyball team. I wouldn't give a crap about economies of scale then.