To me, all three are the modern Myspaces - albeit much smaller and insignificant in comparison to back then. The brands have been around and stand for something

To me, all three are the modern Myspaces - albeit much smaller and insignificant in comparison to back then. The brands have been around and stand for something, which will make it hard to pivot and instill excitement in the user base. To me, all of the three have lost their raison d'etre. Quora had a lot of potential, but only a subset of people actively used the service and formed it into something that won't appeal to the masses. Foursquare was great for the unique check-in/gamification thing, but after Facebook made check-in just another feature, there really wasn't a reason to go to Foursquare anymore. With checkins gone and Yelp being as big and well established as it is, there is even less reason to go there now. Path frankly I never thought had any reason to be there in the first place - no idea how to pivot that thing into anything useful. A "custom-designed, one-of-a-kind bespoke app" if you will...