You're not going to reach the tipping point with just that. Most users don't care one iota about why their lunch is free. They know you feel strongly about that topic, but feel that they just have nothing to hide, that targetted advertisements are really pretty convenient, that they are rather good at ignoring advertisements, that they are not the real target after all with their modest income — that you are just fighting the inevitable based on some vague principle.

The majority at this point in time does not seem to care about privacy, but they do care about the price.

Also, what's the point of moving to just another walled garden? Apple will still keep the service proprietary and closed to third party clients, so you'll also lose the vocal software freedom folk in your approach.