Let me kick off my part of the discussion here with a theme that is less strictly economic than political-economic-cultural. And maybe it's too meta a point in general, but it's what first comes to my mind when I think about the narrowing horizon for the American middle class. It applies all the more fiercely as we confront at least the possibility of another sustained period of darker rather than brighter prospects for the economy as a whole.
As I've mentioned over the years in Atlantic stories, especially four years ago in our 150th anniversary issue and last year on return from three years in China, in a sense I've turned my entire reporting career into a compare-and-contrast exercise on all aspects of the American experiment relative to other parts of the world. One of the themes I've belabored is that all the things the world considers to be "wrong" with America -- it's unequal, it's violent, its people are unlettered, its pop culture is both boorish and irresistible, it has too little regard for tradition -- have been "wrong" for a very long time, and have been complained about by foreign visitors ranging from Frances Trollope and Charles Dickens in the 19th century to V.S. Naipaul in the 20th and Bernard-Henri Levy in the 21st. But, in my view, those traits have been deeply connected to what has been most successful and admirable in the American experience, which is precisely its openness, its ability to absorb talents/ideas/cultures/ambitions and the people who bring them, and its role as an arena for a continually changing cast of people who welcome the opportunity to do things that weren't possible elsewhere.
I won't give the whole spiel about the role of immigration in American growth (and the tensions it inevitably creates). But I think the crucial role of mobility in the American experience can't be emphasized too often. Lots of the things that have always seemed harsh about the American social bargain, including the absence of safety-net provisions in comparison with Europe and the much greater range of cultural/racial diversity the nation contains compared with most other states, have worked out because of the prospect of people moving through the circumstances of the moment toward better prospects for themselves and their children.