[kiloaper]

>then everyone will leave

I don't know. Massive UI changes, a growing creepiness factor and privacy scandals may have caused a tiny number of people, myself included, to leave but I think you underestimate people's ability to suffer through things. To prompt a mass exodus the inconvenience and annoyance caused by ads would have to outweight the huge benefit of social connectivity with a large number of people. There would have to be a better alternative (G+ ?) and an easy way to migrate without losing all your contacts before most users would even consider leaving imho.

[user24]

it happened to myspace.

[kiloaper]

I think Facebook is more entrenched than myspace ever was and that'll make it more resilient. Now everyone is on Facebook not just teenagers, e.g. my 50yr+ aunts and uncles who would have been PC-phobic before. That'll make it harder to leave because of the circles of contacts built up over time.