America and its way of life are under pressure as never before, excepting only the runup to the Civil War of 1861 and the war itself.
We are harassed by extremist Muslims like Osama bin Laden and Mahmoud Amahdinejad, who neither fear nor loathe our country, but rather have contempt for it. That's a new experience.
We're under financial and economic pressure from the Chinese, who sell us almost all the manufactured goods we consume and who want nothing in return except for dollars (so far). The Chinese frankly admit that America has nothing to offer that they would want in return for the tidal wave of manufactured goods generated by their country.
Our high-energy way of life is directly threatened by the rising price and scarcity of oil, a crisis which will one day result in either the total destruction of the American economy, or (in the alternate version) a new burst of energy and creativity resulting in a prosperous yet largely oil-free economy.
Our culture is criticized by religious fundmentalists both at home and elsewhere, people who see only sin and license where the rest of us see creativity and freedom.
And most of all America's political leadership of the so-called "Free World" is collapsing under the strain of multiple unmanageable crises, any one of which could expose once and for all the myth of America as the "world's sole superpower". We can't control Iraq, where most of our Army is tied down in a possibly endless sectarian conflict; we can't control Israel, our supposed "ally"; and we can't control Iran, which is playing a winning hand on its way to domination of the Middle East (and some of the cards Iran is holding were put there by the USA).
So clearly things are going to be very different 10, 20, 50 years from now. The landscape that most Americans think of as "normal", namely post-WWII world characterized by American prosperity at home and primacy abroad, is disappearing as we watch. The new "normal" will be less pleasant for Americans in almost every way. America will be unstable, economically strapped, and unable to stand up to assertions of sovereignty on the part of countries like China, Russia, India, Iran, and others. We will, for the most part, have to take our place in line like other countries.
Someone far more learned than I needs to do a book-length treatment of this topic.