Seth Roberts has posted (and will post) some comments on Tyler Cowen's The Great Stagnation, which I read recently. Both the original by Cowen & Roberts comments to date are very worthwhile. Cowen argues that we've picked the "low hanging fruit" and therefore we may see some degree of economic stagnation in the U.S. for the foreseeable future. Roberts follows up with the pertinent comments, including citing one of his favorites, Jane Jacobs. Interesting and thought-provoking stuff.
I posted a comment on down the line, citing one of my favorites, Thomas Homer-Dixon, who covers similar territory.