The fifth incarnation of the United States...
1) Democratic republic (for whites, at least)
2) More politicized nation with stronger federal government forged by the Civil War
3) Empire, with overseas possessions, beginning with the Spanish American War and annexation of Hawaii in 1898
4) Frighteningly corrupt and bizarre corporate conglomerate, as became frighteningly apparent after George W. Bush's theft of the White House in 2000 and the 9/11 terrorist attacks he exploited so ruthlessly
5) The next stage in the evolution of the United States, which can't be predicted with certainty but will hopefully be an "invisible republic" in the tradition of a campfire discussion featured in the late environmental activist Edward Abbey's book Desert Solitaire.
An Invisible Republic (or fifth republic) would presumably follow a fifth major revolution:
1) The "American Revolution," which ended with an independent United States
2) The Civil War, which freed the slaves but arguably did much to wreck the U.S. as a whole
3) The socialist revolution of the late 19th and early 20th centuries, which did so much to help American workers
4) The "flower power" rebellion of the 1960s and 1970s, which did so much for civil rights and the environment and perhaps helped end the war in Vietnam
5) It will probably take an even bigger movement, whether peaceful or violent, to wrest control of the U.S. from corporations and hold people like George W. Bush and Bill Gates accountable.