So we have come a big circle. In Malay this type of arguing is called "Turning, turning" (Pusing Pusing).
So back to....who is threatening who.
Based on 1962 war document, India threatened China. Thus China was never a threat. For the past 50 years, the Sino-India disputed border are the world's most peaceful disputed border.
Second. Your immediate threat is the internal Maoist insurgent and next is Pakistan which is smaller and just next door.
Third with your current GDP it will be costly for India to sustain such a expensive deterrent weapon system.
Based on all the above, NO India does not need a 8,000km range missile.