Edit:One grim matter to consider; i doubt very much U.S. will surrender its world power numero #1.
But what can they do to stop it???? The inevitable, that is.
The answer is this dangerous country can do far far far more than any Empire that rose and fell before us to make sure another Empire does not replace it.
i feel the deep conceit/certainty of our specialness added to the underlying hard reality this country has for its entire history been a country that is POSITIVE Gawd IS On Its Side, thus i conclude it is highly likely this country will not hesitate to throw the entire world into chaos thru extreme use of the what is without question, the most militarily best weaponed country in world history.
Does this include nuclear, of course it does(we are working hard and harder to perfect strategic nuclear weapons not then to use them if matter don't go OUR way); so yes, we will go nuclear rather than ever surrender our being the world's #1.
The inner mindset of of this country if not us than No one.
I feel those that get any inner hysteria over such and say "O NO it will NEVER come to that!!"
Are victims in deep denial that the world is NOT rational and never will be.
Only difference this time from past history is we got a "Gawd is on Our side" country shifting ever more and more to the right with a MASSIVE group of Apocalyse NOW people firmly in place and growing every month(The Rapturist move is in area of 70,000,000 million and growing).
Our military power is our gurantee we remain #1 or we take the world down with us.
i would strike rational behavior out of all equations myself.