Innovation and Education: A Reason for Slowing Growth?

A while back I argued that the increasing time to educate professionals able to create technical innovations (and therefore growth) could ultimate result in slowing economic growth. The Free Exchange blog at the Economist addresses this same argument. Curiously the piece also points out expensive San Francisco real estate and evidence for a face-to-face requirement for knowledge transfer (using patent metrics) - but these measures don't predict the future.