They don't need to charge for membership. It doesn't need to be black or white. That's what apps are for. You should be asking, would users pay enough for facebook apps to grow their profits?
Facebook has had reasonable success with apps. But the whole app use/discovery/interaction/development experience on facebook has a lot of room for improvement (euphemism to mean it's terrible). And they do seem aware and willing to improve on this arena.
Facebook has had reasonable success with apps. But the whole app use/discovery/interaction/development experience on facebook has a lot of room for improvement (euphemism to mean it's terrible). And they do seem aware and willing to improve on this arena.