Man, I really hate articles like this. What they do is come up with some catchy phrase, like "bubble formation", and then go back in history and selectively pick out a number of examples that fit their "theory" to give it some credence. You can always spot such BS articles because they concentrate on the past and have very little on what the theory predicts. This relatively long article has one paragraph at the end that says anything about what will happen, and that doesn't fit what he said earlier all that well.
It makes for some fun "Golly, Gee!" reading, but Harper's magazine is probably not where you're going to find any hardcore economic thoughts.