I don't think enough is being said that a key difference between the US and the UK is it's geography. It's straddles North America, it has multiple great ports on two oceans, a massive river and lake system in it's center and north, an abundance of resources, and no challenger to it's strength in this hemisphere, though Brazil may approach it. Yes, the manufacturing has gone but with the right plan there is more than enough left in the US to return to that point, if the will were there. What I'm saying is, the US may find itself decline into a multi-polar world, but it will last on as one of those poles for a very long time. Really the only thing at the moment I see changing that is internal strife ripping it apart. And climate change of course, but even then it's so large that various parts will survive. This isn't too sing it's praises but to illustrate that it is a force to be reckoned with, we can hope it will be a paper tiger across the pacific but on it's continent it will have a great deal of muscle for some time. At the very least it's structures will rot but the culture it has created will mean what inherits them could be terrifying even compared to the it's current form. All that is to say it's our duty here to force it's attention away from the international theater to allow movements to grow, and attempt to counter it's evils within, so that at the very least it can be directed towards building a less murderous society than the one it is today. But again, the US landmass is far too large and diverse for me to see it truly slip from power like those of Europe. Decline in the America of "yesterday?" As a force to be reckoned with globally? Not for a long ass time