How long can the USA remain a Superpower?

Current GDP for the US is $13 trillion, growth rate under 3%. Current GDP for China is $12 trillion, growth rate 13%. 5Source CIA) US current account deficit 46 trillion dollars, Chinese trade surplus is 1.4 trillion dollars and rising by 180 billion dollars a year. The iconic US Dollar has fallen 30% in 5 years (12% last year alone) and is still falling. The US economy is likely to be in recession this year, banking is in crisis Shanghai has 21 million people, produces 30% of China's GDP, and has more skyscrapers than New York. And London recently replaced New York as the financial capital of the World. How many years do YOU think before the USA falls from Superpower status? And what happens then?