There's no real way to definitivately answer this. It would be a good subject for speculative fiction.
I think what can be said is that it almost certianly would not have been one united country covering the whole subcontinent, as it (mostly) is now. I can say this because it was not one when the British arrived. Short of external conqest, it never really had been. It more resembled the political makeup of Europe, with lots of kingdoms of various sizes squabbling for power (and the Maratha's playing the role of the Holy Roman Empire).
The rest of the question reminds me strongly of the "What have the Romans ever done for us?" scene from Monty Python's Life of Brian. I'm of the opinion that the area would certainly be different, but probably not too horribly different. Not that it matters. European powers carved up the entire eastern hemisphere at that time, so sombody was going to get India. It was only a question of who.
I know as individual people, it isn't very productive to try to wish our past away. Setbacks, losses, and painful episodes are horrible, but they are the price of living. They make us wiser, hopefully more empathetic to others, and in a way stronger too. Perhaps the same goes for countries. So the easiest thing to say here is that, for good or bad, the British occupation made India what it is today.
