1/ "Silicon Valley has Peaked" is a deeply broken conclusion. What has actually happened is that "Silicon Valley/SF is full from a housing standpoint" because of zoning policies preventing significant new construction. This makes other cities relatively more attractive.
2/ "In terms of physical infrastructure, cities benefit from economies of scale. If the population of a city doubles, its physical infrastructure must increase only by a factor of 1.85. But on the social interaction side, attributes scale by a superlinear factor of 1.15."
3/ Startups and satellite offices of SV firms are not often moving to small towns because of physical phenomenon like energy use and social phenomenon like population concentration increasing optionality. You can wish that that was not true, but that's not in the data we have.
4/ Because cities are more energy efficient, "Cities are the greenest possible way to live together, and perhaps the only way we can mitigate climate change..." "New York is the greenest city in America,” West said. santafe.edu/news-center/ne…
5/ Innovation is NOT decreasing. But “to sustain continued [super linear] growth, major innovations or adaptations must arise at an accelerated rate.” pnas.org/content/104/17… Continued growth does not happen at the same rate if the rate of innovation stays the same.
6/ Many people falsely believe innovation is decreasing for the same reason many people believe that sharks kill more people than mosquitos. Availability bias! A few noticeable innovations from "the good old days" are more available that distributed innovation happening today. 
