I also do not believe in the Anarchism subject. I have my own views as well.
As for the collapse of the "American Empire" - it's already happened. America itself is a shell of the nation it used to be. The current state of it is just a pretty picture that the media tries to portray even as the nation continually falls upon dark times.
The start of this decay began long before the economic decline or the collapse into deficit, before the wars, before the business world throwing itself in chaos due to capitalism.
The start of decay began when the "American spirit" or the definitive cultural identity that America had long built itself up since it's founding had been gradually discarded generation by generation. True nationalism or support for the country which for a time briefly flared has gradually died out, gradually replaced by excessive patriotic zeal for some and gradually disenfranchised, crushed hopes for others. The meritocratic ideals that this country once lived upon has for the most part died out with a gradual drop in social mobility for those who do not have the connections or the resources beforehand. There are exceptions, obviously; however, the country itself has seen an obvious gap in the divide between rich and poor. Something increasingly common in most capitalist oriented economies. That's just the natural order of the economic state of the world when you bind everything under an ideology of consumerism and excessive, un-moderated consumerism. The point is, the cultural basis of the nation is in rot, and unity is either held together mostly by fear and consumerism. The American people aren't producers and they over emphasize their military advantages, frequently leaving the state of their country's economy in the hands of private interests and the free market. This leads not only to more corruption in politics but also more exertions of force on behalf of private interests, often through thinly veiled ideological ploys such as spreading democracy and freedom. America's once rugged, moderated individualism and sense of community, innovation, and hardship (the views that once helped keep this country strong and productive) are dead. The factories which once churned out masses products of products for true export (our import/export ratio is extremely unbalanced) bringing GDP into the country are long decayed with only some sincere production remaining due to outsourcing and the shifting of the economy from once of a balanced producer to a full fledged, mostly parasitic and bloated service/consumer economy and militarily and politically interventionist state.
Private interests, which control many economies and are the pushing force of globalism is the death of society in the sense that we are placing our most important industries and assets as countries into the hands of private citizens in majority control who often prioritize their own aims over the health of their society or the societies of others. The government has become little more than a tool of those interests for the most part - a moderately veiled corporate police state - held together by wars and media which help keep the population in check and complacent, keeping unity together through scaremongering, obligation, and petty issues while the country gets worse. It is a state in organized decay. Neighbor spies on neighbor, police have increasing powers of action as the condition of the nation causes more crime, social inequality, and the one thing that was set to help equalize that for society's benefit - welfare - is gradually being killed off. Contrary to common belief, welfare is not a system of solidarity. It was a system built originally by Otto Von Bismark to appease socialists and workers to help equalize society by keeping the lesser elements in society accounted for so that there need not be fear of rebellion or unrest - and to help curb crime through a widely conservative, noble-led government who wanted to control change and prevent a removal of their social order. The real reason for welfare originally was, and still should be a means of capping the less fortunate, poor, or risky elements of society. The problem it is both abused, attacked by most people who even could use it's benefit, and is constantly being nerfed in favor of individualistic free market views and distaste toward big government.
Another element is that most Americans do not have the heart, the social consciousness, qualification of knowledge or awareness (due to ignorance) to face or challenge their government and officials anymore. The voting base is dominated by often ignorant, or highly polarized extremist elements who bitterly fight over their partisan aims and the two party system is filled with rot and monopolization of political forces by those parties. Any other parties are just a unique nicety that is often ignored by most people.
A major factor especially is how most Americans are increasingly fractured toward each other in their views, in their personal obligations, in their conditions, and in their aims as the society itself becomes gradually oppressive and increasingly become an excessively warped view of social Darwinism where it's everyone for themselves - killing the purpose and meaning of country. To be a united force which works together both out of necessity and reason. That doesn't quite work when individualism is taken to the extreme. More Americans fear for their lives, seek for their own gain, and care for their own aims than they care or consider the fate of the country. Most just want to pretend it isn't there or going on while still screaming with self entitlement over politics.
The social factors, the economic factors, the political factors and the military factors all come together.
The over extended, expensive military campaigns, the expensive bailing out of private institutions to save the economy, and the gradual uselessness of the political system are just symptoms of the overall rot in society.
That's just my view. Apologies for my writing seeming rather fractured. I wrote this hastily as I have to go temp somewhere.