I think Facebook will be a forgotten memory in 5 years unless they diversify out of any fadish type technologies.
FWIW: Apple should start diversifying NOW. People laugh at Blackberry but seem to not realize that the shortcomings of Blackberry 6 years ago are the current shortcomings of Apple. Complacency sucks. Apple will be #3 or #4 eventually. Behind MSFT and Google. Blackberry is atleast diversifying into niche markets right now. Apple is clueless. Thankfully they have cash.