How Things Might Go Wrong
The CIA's National Intelligence Council has put out its forecast on the world circa 2020, entitled Mapping the Global Future. I've only skimmed the interesting read, but I was struck by a pessimistic passage that Matthew Yglesias flagged:
A slow-down could result from a pervasive sense of economic and physical insecurity that led governments to put controls on the flow of capital, goods, people, and technology that stalled economic growth. Such a situation could come about in response to terrorist attacks killing tens or even hundreds of thousands in several US cities or in Europe or to widespread cyber attacks on information technology. Border controls and restrictions on technology exchanges would increase economic transaction costs and hinder innovation and economic growth. Other developments that could stimulate similar restrictive policies include a popular backlash against globalization prompted, perhaps, by white collar rejection of outsourcing in the wealthy countries and/or resistance in poor countries whose peoples saw themselves as victims of globalization.
Emphasis in original. I'm not so worried about "widespread cyber attacks" or "white collar rejection of outsourcing," but you don't need to be a pessimist to imagine there'll be another horrible terrorist attack one of these years.
