I am not assuming anything. People who don't have internt access are not using those service anyways. So those services will continue at their natural pace. So I don't see how free basics will harm the development of independent services.
Regarding Orkut, it had a lot of users before facebook arrived on the scene. But Facebook was just so much better that everyone eventually jumped on it. I doubt the outcome would have been any different had Orkut been free, considering that the network effect was a huge price in itself.
The point is, I am yet to see anyone who can afford a monthly data pack interested in choosing a service based upon it's inclusion in free basics. Free basics is good for those who won't use the internet at all otherwise.