I remember as a teenager hearing in the 80's about "The Population Bomb", and idea popularized by the book of the same name https://en.wikipedia.org/wiki/The_Population_Bomb. It didn't happen. In fact, we are facing a crisis in the world where many countries are not seeing their populations replacing themselves because families are not having enough babies http://www.npr.org/sections/money/2011/11/03/141943008/when-...
Societies and cities are complex entities, as are economies. Perhaps "premature optimization" is a problem in civics just as it is in software development. Better to solve real problems rather than those that might or might not happen.