What is the central paradox of the revolutionary era?

In his introduction to Founding Brothers: The Revolutionary Generation Joseph Ellis defines the central paradox of the Revolutionary era as arising out of the tension between the long-term and short-term prospects of the newly independent nation. In the long-term the prospects for America seemed great. A small group of settlers had defeated the world's biggest military power, an achievement virtually unheard of in the annals of history. The new nation was blessed with seemingly inexhaustible supplies of land and raw materials, all the necessary components for a thriving, prosperous America.
But in the short-term, the outlook was much more bleak. The sheer size and scale of the task at hand, of building a viable institutional structure for the new nation, proved daunting in the extreme; the existing republican institutions seemed incapable of rising to the challenge. John Adams noted that such institutions had only historically been applied to the governance of single cities. But a confederation of states was a whole different matter entirely. It seemed to many that the whole republican experiment was doomed to failure, that the American Republic would disintegrate into a loose system of competing state sovereignties.
That it didn't do so, argues Ellis, is a tribute to the men of 1787, those delegates to the Philadelphia Convention who, in drawing up the Constitution, somehow managed to accommodate republican principles within a truly national framework of government.