I don't buy it. There's no Facebook-killer at the moment to drive these people away, and they aren't going to just give up on social networks... So instead, I think it's something else. Facebook closing invalid accounts, or something.
Would you be opposed to considering the idea that the "social network" fad is nearing its end? We devs tend to see social as though it were a silver bullet for our apps; "Make it social, people love being social!" Maybe people are just rediscovering hanging out in person. I know that I, personally, get no value out of Facebook, whereas I get a ton out of hanging out with people. One other thing that may be contributi…
If I tried to get them to switch to another party planning service, I know the answer will be 'It's too hard to get everyone to make an account there. We've already got accounts here.'