<i>Anyone who beats Facebook is going to have to offer nearly all of Facebook's features and some killer-app features of its own. So any Facebook-killer will make it similarly easy to integrate a FBKiller-Connect feature.</i><p>Examples of this?  Mature market leaders are not usually unseated by someone out-doing what they do best.  They get blindsided by new approaches or market shifts.  No one is going to out-Facebook Facebook, their engineering operations are truly truly amazing.  The agility they demonstrate at that scale is mind-blowing, making Google's operations look easy by comparison.  That doesn't mean they are invulnerable, just that a head-on attack isn't likely to succeed.