facebook has 500 million users and is likely on their way to one billion. is it possible for them NOT to be hugely profitable with 1 BILLION users?
If I was facebook, I would be very afraid of this happening. I understand facebook has some patents on the news feed an other minor aspects of facebook, but their basic feature set is somewhat small, but reproducible.
I think that any social platform faces the problem, that people will jump ship to what ever they think is cooler. Look at Myspace, that was hugely popular and suddenly it become the uncool place to be and then everyone and their moms, jumped ship to facebook. History is bound to repeat itself.
facebook is unique as they are the biggest game in the world with people's real names and real social connections.