How to become, or remain, a Superpower.

First off, it helps to be large, have a large and loyal population willing to pay taxes, serve in the armed forces, and work the industries.  To be large requires political skill to avoid separatism, secession, and break up forces.  The United States sorted this out back in the 1860's, and was able to bring the secessionist south back into the Union and keep them there.  The Russians still haven't solved this problem, they had a third of the old Soviet Union bug out in 1989.  They are still trying to drag it back together.  Sorry about that Ukraine.  If you are small, the big boys will shoulder you aside.  Witness Britain, the mistress of the world thru out the nineteenth century, superseded by the Americans in the twentieth century.  Britain, with a population of maybe 40 million on a smallish island was dwarfed by  a continental power with triple their population. 
   Superpowers get to stay that way by becoming desirable places to live or move to (America where the streets are paved with gold).  Superpowers dominate in things like fashion, popular music, film making, world wide broadcast networks, the internet, inventions and technology, space travel, art and architecture. 
   Good money is a powerful force.  The Yankee dollar is accepted everywhere because everyone knows that with dollars you can always buy what you need from the Americans and anyone else for that matter.  We have stuff to sell, good stuff too, and plenty of it.  And we control the dollar, we can print as many as we need.  That's how we financed World War II. 
   To print good money, you need a large and strong economy that can produce all the goods that the money wants to buy.  And keeps the large and loyal population loyal by giving them good jobs.  With a powerful economy, in good running order, the need for standing armed forces is less.  Everyone knows that a big strong economy can create an overwhelming armed force in short order, so it is less necessary to keep a big force under arms in peacetime.  You need enough force to slap down the likes of Saddam Hussein, but we don't need a force big enough to fight WWIII against the Russians, at least not right now.