I do agree with the "middle class" comment. For years the US economy has supported a very large number of relatively unskilled workers at inflated labor costs. That model worked when the US economy was relatively isolated, but it will not work as part of a global economy. The fact is that the value added by those folks is just not worth very much in a competitive market. If today's economy, you need to be competitive on a global basis, if your job is "portable" and someone else in the world can do it better and cheaper you are toast.

Personally, I'm not sure that a strong economy needs a "growing middle class," as long as the total value added is sufficient. I do think we will see some changes to society in the next couple of generations, and I do suspect there will be a larger gap between those contributing to the overall economy and those in the service sector. Keep in mind that the US population is only about 7 percent of the world, there are plenty of markets out there.