Social networking may be the most notable phenomenon in internet
history. Few trends have grown as fast and gone as a far, and it has in many ways fundamentally altered the way hundreds of
millions of people use the internet.

But have popular social networks like Facebook tapped out most of their
growth potential? According to a new eMarketer report, the answer may be
yes.

Currently, just under 64% of the internet users in the United
States use social networks. By 2013, that number will increase to 67%.
That’s growth, but it’s not the double-digit growth we’ve become accustomed to
seeing.

The slower growth is due to a simple fact: so many are already using social networks. This year, eMarketer estimates that “over four out of five 12- to- 34-year-old online users will be regular social network users.” In the 18-24 age range, some 90% of internet users will get their social network on. And social networks have significant penetration amongst older adults as well; over half of internet users 45-64 will use a social network in 2011.

Clearly, social networking’s reach is formidable. But the already-impressive reach also means that there are fewer and fewer internet users yet to be convinced to sign up. And, given how long social networking sites like Facebook have been around, it’s logical that at least some of these users will never be persuaded to sign up, for a variety of reasons.

According to Debra Aho Williamson, this means one thing: “with fewer new users signing up, social network users will be more sophisticated and discerning about the people and brands they want to engage with.” And social networks themselves will have to work harder to maintain loyalty, “particularly [with] people ages 35 and older.” As Williamson sees it, this creates plenty of opportunities for marketers and publishers:

Marketers and media companies can contribute to this effort by creating compelling user experiences that make people want to stay connected to social networks so they can gain access to experiences, deals or content they may not be able to find anywhere else.

From movies to commerce, it’s clear that more and more media and marketing will find its way onto the social network. But is that going to boost social networks, or could it hurt them?

In many ways, social networks are growing more and more impersonal by the day. Instead of serving as platforms for interacting with other people, social networks are increasingly serving as platforms for interacting with brands, businesses and entertainment.

When it comes to the world’s most popular social network, some believe Facebook is starting to look an awful lot like AOL reincarnated. Perhaps being able to watch movies, buy flowers and play games in a single place will eventually lure those who haven’t yet been attracted to the social networking experience, but the more ‘crowded‘ and ‘cluttered‘ social networks become, and the more they try to be all things to all people, the more they risk driving their most loyal and valuable users away.

From this perspective, the question may not be “How much bigger can social networks get?” but rather, “How much bigger should they want to get?” Now that growth is slowing, perhaps companies like Facebook will take the time to consider this question.