I would class social media as a symptom of a broader class of social estrangement that makes democracy less viable. Why, today alone on Hacker News we have articles like "Alarming Decline of Quality Youth Playtime" and "Rural America's “brain drain”: How student debt is emptying small towns". There is a general trend of less engagement in community, and increased segregation by social class. People engage with social media because that's all they have left.

Without the daily "forced" interactions with people of diverse backgrounds and intelligence levels that come naturally through proximity, and with all communication centralized and mediated by something that allows you to easily (even transparently) avoid challenging viewpoints, small wonder that society becomes segregated and unstable.

Really, I think the solution is small, walkable, community-oriented towns, preferably alongside the abolition of cars. Solve that, and nobody will care about "social media".