This is only about the US. The US isn't the only country in the world. Or the most important. Or the largest. Or the richest. Or the most anything. The US has been declining for decades, and the decline is continuing. Nothing new there. It is being replaced by other countries, including the BRICS. Stop focusing on the US if you want to understand what is going on in the world.
The US is by a huge gap, the most powerful nation...and that can more than make up for the fact that it is not the largest or allegedly not the wealthiest.
The US is the wealthiest, but only because other countries still allow them to be. its keeps order and change is scary. But a few inevitable structure changes and simple announcements by russia and china can change all that in a split second. America is all that it is because other countries still allow it to be. (Currency). Dont piss off the hand that feeds you.
What would russia, and china be, without export and import to US and others? That's the question. It's called 'dependency'. It has a degree. That degree is what determines whether or not your 'split second change' is realistic. In the very end, 'power' is derived from independency i.e. the ability to do it, without the rest.
Not export and importing. They have the power to decide which is reserve currency. Being reserve currency is the ONLY thing america has going for it. countries are slowly starting to trade in chinese yuan and their own currencies. If america loses that status the country will fall to its knees. Every country leans on the next. Of one falls we all fall. Its impossible in this day and age for any country to be completely independent. Well north korea is trying and they are giving it a good shot.