It is this concept of entertainment that makes Facebook what it is today. A single source of entertainment, and a place to peak deeper into the lives of those around you with or without participating in those lives. As with many different forms of entertainment if you indulge too deeply you are consumed by your indulgence.
For the time being Facebook has a place on the internet. Will it be a main stay for years to come? Well that is very hard to predict. I truly believe Facebook's biggest internet value add will come in the form of an online digital pass. I feel those leading Facebook's directions also believe that too. If they can satisfy the majority of its users basic desire for entertainment, continue to build out the graph API, and keep giving more reasons for businesses to utilize the graph API then soon enough Facebook will will realize what Microsoft never was able to with the Microsoft Passport from the Internets early days.