Nobody has mentioned the obvious alternative to Facebook, which has been advocated by Max Schrems: forcing Zuckerberg & company to open their data formats, allowing compatible competing services to interoperate with Facebook.
Open standards are the solution we've favored historically - with most of our mass media (telephone, radio, TV), and even with many physical systems (snail-mail, railroads, air traffic control). In the case of social media, MyBook.com could offer a paid service that would maintain privacy, yet allow posts to interoperate with those on Facebook (subject to whatever degree of granular user control). CheapBook could offer less privacy, at lower cost. FancyBook could offer a nicer UI. Etc. GoogleBook could even allow Google to compete, something they've been unable to do so far.
Facebook is not the leader because it's so utterly fabulous; it's the leader because it's been allowed to turn a useful public service into a de facto monopoly, with ironclad user lock-in. That's not Facebook's choice to make - it's ours. And we can change our mind any time we like.