With the knowledge that the individual is society, rather than a mere participant in a movement guided by external forces, I believe that the old saying of "the more things change, the more they stay the same" is spot on.
Since the signing of the Declaration of Independence, the American people have been shaped by a variety of social uprisings. Some of these led to terrible events, such as the Civil War, while others brought about positive change, as did the early twentieth century's Progressive Era. Despite these radical shifts in popular sentiment, a single fact has always remained: no two people can independently agree on every issue. It is for this reason that social change is inevitable, and a new wave of ideas never fails to be in the works.
American society is extraordinarily fluid due to the American people being so. Trends, from merchandise to politics, come and go faster than the seasons change. The unique actions of equally unique people are what make this happen, with the tenets of individualism passed down through succeeding generations as a driving force. Even collectivists, by virtue of nature, retain shreds of individuality as humans are beings designed to look after their respective self-interests. Only the development and consequential spreading of self-defeating dogmas and ideologies keep a voice yearning to be free silenced within the depths of many a collectivist soul. Failed partisan movements, from Leninism to Nazism, are sobering reminders of this.
It is safe to say that the pages of history books yet to be written will be filled with the triumphs and tragedies of yesteryear, only with different names and places. Come what may economically or demographically, the America of tomorrow, and beyond will be not so different from what it is today. From a broader perspective, it should be more than a little similar to the way that it always has been. Einstein did say that the difference between past, present, and future is but a persistent illusion.
As society ourselves, we should have figured this out a very long time ago.