Niall Ferguson says we have 6 years left

American politicians don't have a sense of urgency, Ferguson contended. They feel the country can limp along for another 20 years or so in its current financial health without making tough decisions about fiscal policy. He believes they are wrong. The federal government's debt has grown so large in the past decade that the United States will inevitably devote an increasing amount of taxes to it. Meanwhile it's facing a greater burden through the Medicare and Social Security programs as Baby Boomers age. It's also currently fighting two wars. All that while revenues have plummeted in the recession.

“If you really want to see when an empire is getting vulnerable, the big giveaway is when the costs of serving the debt exceed the cost of the defense budget,” Ferguson said. That will happen in the United States within the next six years, he predicted.

To add to the doom and gloom, Ferguson said the collapse could come much quicker than people realize.

“Most empires collapse fast,” Ferguson said. “They're complex systems. They exist on the edge of chaos. It doesn't take much to tip them over, and when they tip over, they fall apart really quickly.”
--http://www.aspentimes.com/article/20100706/NEWS/100709901/1077