Fifteen years sounds about right to me. I tend to be a believer in historical, generational cycles, from the Kondratieff wave to even some of the sort of tin-foil literature on cycles like The Fourth Turning (which I have not actually read). While I can understand skepticism of this kind of analysis, I am of little doubt that national psychology seems to go through huge generational shifts. For example, virtually ever one I know whose grandparents suffered through the Great Depression remember them as pack rats, storing stuff that would strike us as disposable. Most of the generation is now dead, and their experience largely forgotten.
The approach of that generation towards "stuff" is basically the polar opposite of our generation's willingness to junk something at a moment's inconvenience to buy a new one, but I think we are witnessing the very beginnings of a shift to that generation's mentality. Over the last few months, I've noticed a pronounced tendency in the media to celebrate the coolness of being frugal. The hipness of frugality will subside as things worsen and frugality becomes a requirement rather than a fashion statement. I'm afraid that when our generation emerges in the 2020s, we may not think so differently than our grandparents, and, unfortunately, that kind of polar shift in psychology can only come as result of severe national trauma. Which, as you know, I am forecasting.
The optimistic counterpoint is that might see a renaissance for our republic as people start to spend less energy debating the American Idols on TV and more debating the American Idles in Congress (god awful pun copyright Gammaboy 2009). Perhaps we might actually see more from real political thinkers in Congress (RP to start) rather than the daily idiocies of clowns like Barney Frank.