In the past I have posted extensively on what I think will be the most likely outcome of a retrenchment by AMerica from global affairs.  Here are several representative pieces:

Will Atlas Shrug

Welfare at Home, Weakness Abroad

Forget Utopia

Why do I mention these pieces.  Because now Zbigniew Brzezinski, one of the foreign policy establishment (and for those that believe in Black Helicopters, one of the founders of the dreaded Trilateral Commission), is writing about it in Foreign Policy magazine and is soon having a new book come out on the subject.  

Note this,

"For if America falters, the world is unlikely to be dominated by a single preeminent successor -- not even China. International uncertainty, increased tension among global competitors, and even outright chaos would be far more likely  outcomes...

...No single power will be ready by then to exercise the role that the world, upon the fall of the Soviet Union in 1991, expected the United States to play: the leader of a new, globally cooperative world order. More probable would be a protracted phase of rather inconclusive realignments of both global and regional power, with no grand winners and many more losers, in a setting of international uncertainty and even of potentially fatal risks to global well-being. Rather than a world where dreams of democracy flourish, a Hobbesian world of enhanced national security based on varying fusions of authoritarianism, nationalism, and religion could ensue."