Agreed. Facebook may have momentum (700M+ users), but it has terrible ratings from users[1] and developers[2] alike. I will be very surprised if they are a major contender five years from now.
[1] - http://abcnews.go.com/Technology/facebook-webs-worst-custome...
[2] - http://techcrunch.com/2011/08/11/facebook-wins-worst-api-in-...