As Facebook turned 10 years old this week, you have to be impressed by what this company/movement has done to our social world. See, for example, Hanna Ingber's blog post by the New York Times Bits Blog about the 'transformative power of Facebook.'
But, you have to also wonder what the FB of the future will be like? And, will it even be Facebook that continues to serve such a key role? For hints, see the Mashable stats on how many teens are leaving (or avoiding) Facebook. Other media allow them (pre-teens and teens) on earlier and since FB is what their parents are doing, they want to be different. Plus, Facebook's interface is not as simple as others. If Microsoft would have learned the lesson of simplicity say 20 years ago, or even 10, it might not be in the shape it is in today. Once folks have seen simplicity, there is no going back.
There are also cultural alternatives to Facebook. See, for example, consider the massive uptake of Weixin or WeChat in China and around the world. See article.
In 10 years, social media has gone from the curious fringe to the mainstream of day-to-day life for billions of people around the world. Platforms like Facebook have taught and allowed us to share our thoughts, feelings and photos with those we love and with those we don't even know and those we probably will never meet.
However, just as Marshall McCluhan declared 40+ years ago, 'the medium is the message,' which means the choices we make about 'how' we communicate--i.e., through which social media platform we communicate--are as important, if not more important, than 'what' we say or share with others. That is why Facebook will continue to be the standard social media platform for a while, and why new platforms will no doubt emerge.