I think it all depends on how you look at it. I don't think many people outside or even inside India will consider India developed by 2020. Maybe by 2030-45.
I think a huge factor is poverty, once levels are below 15-20% India can be proud of itself and can be consider itself developed to an extent. The way things are going ie a year on year 1% reduction in poverty levels in India which should accelerate in coming years- in most of our lifetimes we can see reasonably low levels of poverty in India.
India will only be developed when literacy rates, life expectancy and per capita incomes increase dramatically.
Like I said- 2030-45 is a more more attainable level. 2 decades of 5-6%+ economic growth will see things go this way.
And sir it's not about the headline grabbing infra projects like super talls and metro projects in the mega cities. But about village level power, decent road connectivity wherever you go in India, higher Internet users per 1000 Indians, more university enrolments, improved healthcare for all, great infrastructure in tier 2 and 3 cities etc etc. Delhi,Mumbai, Bangalore and a few others by 2020-25 will be a world class cities by many counts but what about the rest of India? No one can get left behind in new India and here must be trickle down effects.
The problem with this country is that there are way too many people! It is an unpleasant shock as to how many people are packed into an area that is day by day proving to be quite inadequate to handle them all. It is a vicious circle really. The more people you have, the "quality" of people decrease which in turn is responsible for more births. People are still not educated enough to collectively bring down the fertility rates. What India needs is literally some quick de-population. It sounds harsh but that is the way to go.
In some years I doubt we will be able to manage so many people and I seriously doubt we will have enough land to house that many. House prices are anyway currently out of reach for the middle class guy, I shiver when I think what will happen even 5 years from now. A bit off topic, sorry for that but you brought up some points which got me thinking