It will take atleast 50 to 60 years with wise policies for India to reach per capita income USA enjoys today.
The key phrase is 'wise policies', else it would take much longer. Let us get rid of this 'being superpower' small talk and dwell on complexities inherent in existing realities and policy abstractions.
Let there be proper decisions to control inflation, reduce trade deficit, next-gen reforms, sensible power distribution policy, micro-finance, electronic money infrastructure etc