Couldn't happen to soon. Being the worlds super-power with troop garrisoned all over the world is provoking a lot of corruption or our original principles as a nation. After the legacy of death squads, 'signature' drone strikes, Abu Ghriab, etc, a person would have to be a complete imbecile to buy the BS about our 'spreading freedom' or whatever.
It can be legitimately argued that our empire provides 1/4 of the world resources to 'us', but the spoils of war are increasingly mal-distributed so more and more it's the trailer trash that does the dying and the Wall street types that do the wealth accumulation.
As a nation we've got great resources and infrastructure within our borders, and lack a lot of the problems that the Chinese have (especially overpopulation.) We have the potential to provide a decent quality of life for all of our citizens, or those who will do the bare minimum to participate at least, so I don't fear a fall from our lofty current situation. There will certainly be an internal struggle to see what class shoulders what percentage of the reduction in inputs (hence ballooning police state apparatus) which is my main concern.
I have pretty close to zero concern about some Chinese guy showing up on the coast and making me suck his dick. Some honky from Washington DC doing so is a vastly bigger threat to me.