The US does not have to ride away in the sunset
I do not see things in America that bad since as life-long consultant with much workout experience I am used to immediately look for the reserve of important things that seems feasible to correct and that could generate a turn around. This particular reserve seems quite large in the US, and I am not just referring to the Iraq war.
If the US would though taxes raise their gasoline prices to European levels; put some corrections in their runaway health-sector costs; reform their bankrupting tort system; not keep over two million of their citizens in jails or prisons; accept that when the check arrives is not the best moment to sent away those who might help you pay it, like the immigrants, then we would have to conclude that the US has still a long way to go as the empire. Of course if the US can't find it in them to correct those things, it would indeed be riding away in the sunset in a The End, but then this would also not really be because of economic problems but because of something totally different.