I wud definitely believe that India could eventually become the world's superpower. There have been several things thay've been working on over there that would re-inforce that theory.
A country that has the capacity to project dominating power and influence anywhere in the world, generally characterized by strong growth rate, defense power and foreign influence and so may plausibly attain the status of global hegemon.
I am agree that Japan can be the next super power. But still i am an Indian so i would like to say that India may become next super power. Our strength is the young population of our country and it can boost the GDP of our nation and also India is the fastest developing country.