American 'Declinism'

Is America in decline? Has it been in decline? These are questions that many ask and debate with eachother over small events that have happened to have occurred over the last three hundred years of American history. Some argue that, especially recently, America has overstretched itself by going to Afghanistan and Iraq, not to mention the many other countries that American troops are already stationed in under Humanitarian aid. The defence budget for America is averaging at 900,000,000,000 dollars. The rest of the worlds defence budget combined is more or less the same.
http://rationaloptimist.wordpress.com/2008/06/30/american-declinism/
Frank S Robinson a self proclaimed rational optimist, Humanist, and classical nineteenth century Liberalist, believes that America is not in decline. In fact America is an exceedingly rich country that is financed by its exceptional productiveness. Robinson does not seem to be worried with the ten trillion dollars worth of National Debt that every minute gets added to. He seems satisfied in the knowledge that the productiveness of America will keep it forever afloat.
Even with the mounting costs of the pension, healthcare and social security and the fact that he himself acknowledges that the national GDP is $14 trillion with up to $95 trillion being spent on the previous expenditures alone. This does not matter because according to Frank S Robinson, (who incidently sells ancient coins for a living after retiring from being a judge), all the tax that is taken from the citizens would more than pay for these expenditures from the State. If cuts need to be made then it would only be the people who wouldn't miss the 'free benefits' that would lose out.
This is a typical view that I have come to find whilst researching American declinism. The American people are so entagled in their own way of life that it does not occur to them that there is no real need for these massive expenditures. It has not escaped my notice that the defence budget rose considerably after 9/11 in foresight of the attack on Baghdad. The new Healthcare bill that was pushed through by the Obama Administration will be another burden on the tax payers, which at the time of writing this article Frank S Robinson had no knowledge of. Many of the people of America were enraged by this policy, however it would be more beneficial than many of the drains on the countries finances.
What I did find astonishing was the acceptance that America may not always be exceptional. Robinson states "And someday, China may become more powerful than the US, and maybe even richer too; but that won't be the end of the world either... America will not starve..." I found this slightly against the grain, for on one hand he is arguing for America not being in decline, however, in many Americans eyes they are at the top, surely if they were to be overtaken by China that would essentially be America in decline?
It seems to me that he is trying to cover his bases and in the mean time he is contradicting himself in a rather amateur fashion.