This ignores the fact that the current Silicon Valley has none of these things. Palo Alto has a 3x4 blocks region of low density apartment buildings alongside s

This ignores the fact that the current Silicon Valley has none of these things. Palo Alto has a 3x4 blocks region of low density apartment buildings alongside storefronts, and that's all encircled by single-family residences. Right now, only NY and Chicago (edit: and Boston) have anything in the US that really can claim to be high density. Most of the other "next valley" candidates are not set up to be high density, at all. The real test is that it should be easy for a person to have all of their needs and most of their desires met, while choosing not to own a car. They should not be unreasonably burdened by choosing that. SF is barely passing that test IMO, being a non-car owning resident here, but it's getting better. The other city where that might possible is Portland, and from what I recall of Austin (it's been a while) it's not nearly dense enough to support this.