In order for a competitor to overtake Facebook they would need to provide added value, expand their user base extremely fast, have solid reliability, and hope their founders can resist the urge of selling out to a larger corporation. Back in the days when Facebook started standards were low. Personally I know many people who moved from Myspace to Facebook simply because HTML was too confusing. Facebook has brand recognition and it's impossible to make all your friends/family move onto a new service. A new rival competitor would have to start out with small groups of "technology-savy" users who vet the service and slowly convince friends/family to migrate; giving plenty of lead time to cash out of the stock. Today it's more profitable to create tech demo disrupt services that get bought out.Facebook's biggest risk is itself. Just a few years ago there were so many new features being added that it drove people away but lately they seem to have their act together and are streamlining and simplifying the experience. I'm a holder of the stock until Mark leaves the company. These types of high value companies are just vehicles for their founder's ideas and their high valuations live and die by them. As with Amazon and Bezos, Apple and Jobs, Google and Page/Brin I would expect growth to slow without them.
