The author seems to completely miss this. AOL didn't die because it was bought by TW, it died because broadband became commonplace and people realized there was much more to the internet than AOL's walled garden. Myspace died because it was the last vestige of the "personal homepage" style internet and never ran with its burgeoning use as a network for musicians.
Facebook will fade when the next major gap in social connections+communication is filled. Simply saying "something more popular than Facebook will happen" seems a horribly obvious and empty statement. Now talking about what we still need or might discover with connections would prove insightful, but of course no one's going to blog about that until it's launched.