Taken as a whole, the European Union is already a superpower. Europe statistics compare fairly well, though maybe not as strong in GNP or Per Capita Income as they do in America.
Country Population GDP Tax Revenue Military Spending
USA 278,058,881 $9.963 trillion $1.828 trillion $276.7 billion
European Union 378,714,991 $8.478 trillion $3.006 trillion $165.677 billion
In the next fifteen years, if Western Europe properly invests in the development of Eastern Europe, maybe… 5-8% each year, a combined Europe would become a very powerful superpower.
If unified defense and foreign policies join unified economic policies within the EU by 2017 then the EU would have:
Country Population GDP Tax Revenue Military Spending
EU 483,714,991 $10.828 trillion $3.789 trillion $208.8 billion
(data taken from http://www.geocities.com/muffins4brains/EUsuperpower.html)
With economic growth, the United States would not be far behind and might surpass Europe by reaching the $11 trillion mark by 2017 if we invest in current productivity in future growth. This still leaves open the possibility of a Chinese or Indian Superpower across the Pacific Ocean.