Good article, though i disagree with his conclusion that natural unemployment is going to fundamentally change. He is arguing that the economy is in a state of change and the losers in this creative destruction are those in low skilled jobs. so that explains the currently high unemployment, but to argue that we are at a new natural level doesn't seem justified. As the population (albeit slowly) retrains to participate in the higher skilled labor market employment will rise.
This is somewhat similar to the classic dismal science (http://en.wikipedia.org/wiki/The_dismal_science) argument. Even though there is high unemployment now arguing that the economy cannot find a use for these people seems very short sighted.
Modern industries take a lot more training than those of a century ago. At the very least, the time to retrain will be longer than in the past. That alone would lead to higher unemployment. More importantly, there are more people who, for whatever reasons, just aren't capable of becoming good engineers, scientists or business people.
This is somewhat similar to the classic dismal science (http://en.wikipedia.org/wiki/The_dismal_science) argument. Even though there is high unemployment now arguing that the economy cannot find a use for these people seems very short sighted.