The U.S. will still be the sole hyperpower once the next phase of global unrest is finished.
Of course, what the "U.S." looks like at that point may be markedly different from the contiguous continental + Alaska, Hawaii (and Puerto Rico, for all intents and purposes). Secession overtures will probably increase, both from states or blocks of states wanting to secede and from states or blocks of states wanting to eject weaker players. It remains a remote possibility, since bloody precedent was set the last time the issue was raised.
But still, I am optimistic long-term. No other nation or "Union" comes close to the cultural and legal institutional infrasctructure the U.S. enjoys. This hyperbolic talk of massive inflation and being slaves to our debtholders is silly and counter-productive. However, the austerity measures (putative and already active) will guarantee more pain ahead. The world is witnessing the slow phase-transformation from cooperation to competition. As I have said before, humanity does not "progress" in some linear form like scientific discovery...and our inability to recognize this false analogy will not prevent the cycle from changing again. Relatively speaking, peace, cooperation, and order has had a wonderful nearly 80 run.
So when the EU fails and recedes back into its traditional adversarial relationships, when China blows up in spectacular fashion under labor unrest, institutionalized corruption, and closes shop for a few decades, when Caliphates are re-established, when Russia re-starts Imperial ambitions in the Baltics, etc...where on earth is capital going to flow where it can enjoy a stable environment in which to survive and grow?