FB is at its pinnacle, under the law of nature, when things reach at their pinnacle, the only logical assumption is for them to come down. Unless FB comes up with something new to drive the adrenaline of those who invest their time playing with FB, it is bound to slide downward. It's all nice to see pictures of old friends and acquaintances, but those types of social interactions only exist where there is less economic activities with plenty time to spare.
However, where there is disposable income nations, people spend quality times with family and friends at the present, for time has a different meaning to people with money. They see time as their enemy for it's having to choose between making money and spending it with friends and family, so for them FB is a no go. In countries with plenty of money, very little social interactions are observed, individualism takes over, and where there is no opportunity and very little disposable income there is plenty of social interactions.
Hence, the people that use FB are not people that have income to make this venture a lucrative one. It is a nice business venture, and very creative at its core, but for North American and European kids between the ages of 11 and 17 to maintain contact and call each other funny names. I have seen my nephews and nieces do it. I must admit though, it has one excellent use, it teaches kids how to sit in one spot long enough to express themselves through sentences. Let's not also forget the role it played in the Arab Uprising.
All in all, it's a good service for libraries to have for unemployed people and kids to come and use the services. So, government needs to own it, rather than for corporation or individual business venture to have it. Then again, its not beneficial for governments to own and make it available freely, for it robs time, and time that can be used to increase government coffer size, so politicians can enjoy spending the money, sometimes creating conflicts and other times prolonging the suffering of people by purchasing hit-men like Meles Zenawi.