Is India becoming a superpower?
Well, that is an interesting question, yet to me the more interesting underlying question is how is global power distribution changing as a whole.
And it clearly is moving away from the historically unusual situation of a single superpower to a more multipolar world with several great powers.
Lets look at some significant factors.
Now to me it is clear that in the near future India will become a great power, but a superpower needs great capabilities and dominating influence in all the folowing spheres.
Political, Geography, Cultural,Military, Economic, Demographic.
India has already reached superpower like status in Geographic(land mass) and Demographic terms. Now the rest is not superpower territory and not even great power for most categories yet. But if India continues it steep rise in economic terms over the next 2-5 decades and deals with the horrible poverty the other categories will follow suit. Cultural beeing the only thing that is not pretty much automatic.
From what I've read I see 2050 with the US only beeing one of 4-5 Great powers. China, India, EU, US and Brazil(if they manage to get their stuff together in Latin America). I see no single power beeing dominant in all spheres (superpower) for that time and Russia going downhill even further (all indicators are there).
That is if no additional world war breaks out, which seems highly unlikely at this point of economic interdependence.
So no, India is not rapidly becoming a superpower, rather a great power among several.