I think there's a possibility it would resemble similar industries like mobile services - you would subscribe to a social media service provider of your choice

I think there's a possibility it would resemble similar industries like mobile services - you would subscribe to a social media service provider of your choice and you'd use their service which is interoperable with other social media service providers. They could sell different monthly plans with some amount of allowed photo/video uploads, messages, etc. To us it might sound strange now, but it would feel entirely normal to people in a world who never experienced free services powered by spying. Not sure if that would be better or worse than what we have now.