This may be much too serious and heavy for this site, but let's see!
I have been hearing lots of news about a new book that documents the fall of American civilization by comparing it to the waning days of the Roman Empire. Many times, these comparisons are weak but this guy has many excellent points. Be aware that I am biased, I have believed in this decline for over a 15 years. Some points he makes, my apologies if I don't get them all exact, are:
1. The selling off of government. Our government has been for sale for quite a long time, accelerating in the last decade or so. Every politician is for sale to the influence that benefits him/her the most. This leads to massive corruption and crimes. Leaders of government become weaker and weaker. President Carter, although a smart guy, was an extremely weak leader. Bush the First was OK but again, a poor unfocused leader. Dubya is the dumbest president we have ever had in our history, sort of a Nero without the (warped of course) brains. Congress? Well choose any at random and you won't be happy. All of this weakens the United States severely. The same thing happened in Rome.
2. Our military is too small to do the tasks required by our weak leaders. This leads to ineffective measures and non-completion of campaigns. More and more of our vital military functions are being outsourced, from the Cheney-led no-contract bids for Haliburton to the infamous Blackjack squads to the use of foreign "secret" prisons and interrogators. We are also left weak at home as more and more of our resources go out of the country trying to hold the entire world together. These actions lead more and more countries to oppose our country. We blame them but it's really us. The same thing happened to Rome and their military as they tried to control their world. There was a reason that the hoards crossed over the hills of Rome without significant opposition.
3. There is an increasing gap between rich and poor with the middle class disappearing. The situation has now become worse than even during the Great Depression. That trend is continuing at an accelerating rate. In Rome, at the time of its fall, about 1% of its citizens were moneyed, the rest were dirt poor thanks to ineffective and selfish government (see 1, above).
4. Education in this country has become worse than it has ever been. We are now dead last in the first world in many subjects, we are even falling behind some third-world countries. No Child Left Behind is a tiny silly band-aid on a huge gash. About 25% of Americans can't find the United States on a world map! They have no idea where Iraq is, or Europe, or Russia. Math is a disaster, fractions are beyond the capabilities of almost half of all Americans. While our 8th graders are still working on fractions and proportions, students in England, France, and Spain are doing pre-calculus. Graduates with a PhD in science, such as physics, spend years as a post-doc in the United States or emigrate to get a real job. Superstition is used to create science public policy while science is ignored. The New York Times had to lower the reading level of their newspaper years ago because reading skills have declined so much. Lack of real education also weakened Rome as they glided along on momentum rather than creating new ideas and basic research.
There is so much more but this gives you an quick idea. As Doctor Who would say, "Nothing lives forever, not even Time Lords."