the real challenge is gaining a critical mass of users. Facebook, with its 2.2 billion users, will not disappear, and it has a track record of buying or diminishing its rivals (see Instagram and Foursquare). But as Lyft is proving by stealing market share from Uber, and as Snapchat proved by taking taking younger audiences from Facebook, “network effects” are not destiny. Now is the time for a new generation of Facebook competitors that challenge the mother ship.