1. India certainly has a good economic outlook with what is going to be the biggest workforce in the world if all goes well in a United India starting from a date like the 1920's or 1930's. Yes, India will be stronger if it doesn't get itself into wars. But the key in making India a great power-I know this is about getting India stronger but bare with me- and sustainable they must keep their population below 700 million at least. Overpopulation is going to use up resources at a staggering pace and this leads to widespread hunger and instability. India has to make contraception and family advice an affordable product before the Green Revolution that will increase crop production around the world. It is nearly impossible in any TL to have India create a silver bullet in technology that will magically feed all of it's one billion people and create enough resources to meet demand for the giant middle class and upper class.
2. I'll agree with you there
3. Yes a lot can change. India will be right next to Iran, are they going to save the Phavlavi Dynasty or not? Unless they free Tibet and let Burma go, they will share a bigger border with a China, how will things go if China is communist or nationalist by that time? And Afghanistan, the nation that has been unstable since at least the Great Game era, what will India do about that?
And yet none of those factors will detract from the fact that India would still be stronger. Of course India will have issues....I AGREE with you on many of these things. China, Iran, Afghanistan.....they are all factors that could affect how strong this stronger India would be. But the fact remains....it would be stronger. Now education, poverty, corruption....all these things need to be figured out, and of course it is going to be a lot of work. But as India becomes independent, you'd see a lot of aid going to it from other nations, invested in maintaining their bulwark against communism. Trade would be a huge deal. However, a lot of military spending won't need to be spent due to no true threat outside of China existing.....a lot of spending which would be allocated to other programs.