James Fallows has written a fascinating piece on How America Can Rise Again which turns conventional wisdom on its head. Most people seem to worry about economic competitiveness, global conflict, and social degeneration, and all cling to the unifying principles of the US Constitution (albeit with differing emphases).
Fallows argues that this is a-historical and unnecessarily pessimistic: Americans have always worried about falling short, and have always muddled through. The biggest threat is not that the American people will fail to adapt and innovate, but that the increasingly inflexible and undemocratic nature of their political institutions will make it more difficult to implement the necessary changes:

The Senate’s then-famous “Gang of Six,” which controlled crucial aspects of last year’s proposed health-care legislation, came from states that together held about 3 percent of the total U.S. population; 97 percent of the public lives in states not included in that group. Just to round this out, more than half of all Americans live in the 10 most populous states—which together account for 20 of the Senate’s 100 votes. “The Senate is full of ‘rotten boroughs,’” said James Galbraith, of the University of Texas, referring to the underpopulated constituencies in Parliament before the British reforms of 1832. “We’d be better off with a House of Lords.”