Perhaps the answer is to make the concept of social networks no longer cool; or even make them undesirable. I think it's pretty clear they are not, anyways.
I use whatsapp, line, email and photo sharing services that allow me to easily share and communicate thoughts and media with exactly who I want. It's more personal, not addictive, creates better relationships, and helps me focus more on who I am rather than how others perceive me. And of course I don't have to use facebook and be a part of all its oft-criticized problems.
For hundreds of millions of people Facebook is the messaging system. There's postal, telephone, email, FB messaging. It's also the most used. I think you need to come up with solutions that assume it, or an equivalent, will continue to be a principle and primary means of communication for billions of people.
If people would stop using FB, rather than complaining about it, perhaps this would not be an issue?