I wonder if the current Federal Government hasn't fallen into the role of an empire of colonies (the 50 states and possessions).
I say that, because enormous taxation is levied on the states, to benefit those the government sees fit to benefit. Wealth is gathered into select (and possibly corrupt) hands. And the rights of the states to participate, to voice their conclusions, to object, has been shuttered.
Where in a republic, as I understand the term, the states collectively assign responsibilities to an overarching government, what we have today is an oligarch that arrogates powers and authorities to himself. The President, and at some level the Congress, have dismantled the relationship of Republic between the Federal Government with and among the states.
The problem I foresee is that colonies don't remain subservient forever. They rebel, establish their own priorities, take up responsibility for meeting their own needs and goals.
This thought occurred to me while reading the ArchDruid Report dated February 22, 2012. John Michael Greer holds a systems view of society and culture, and governments. His post contends that it is free trade that dismantles empires; I think instead that free trade is one of the arms of colonial management that exacerbates a transitory relationship. Colonies form, develop, and go their way. Empires, I believe, are inherently unstable. Either they grow or die, and each region of the empire likewise grows or dies. Any regional weakness weakens the overall empire; every regional strength accelerates the day that empire as a form of government will collapse due to conflicting interests.
The states of the United States flourished as members of a republic. I think now that the electoral college is probably one of the strengths of that republic. When US Senators were no longer selected by states but by popular election within states, that was a drastic move toward dissolving the needs of states to mind their own businesses within the frame of a republic.
Free trade among the members of the republic, the states, has shown itself to be a good thing. But I shudder to think what free trade does to empires, as the US slides further from a republic form of distribution of powers.
This might be at the center of a "no nation can long endure" moment that faces us now.