This aligns extremely well with what I have seen with my teenagers and their friends.

Recently I was at an event where a teenager was giving a speech in which he mentioned Snapchat or Instagram and said, as an aside, "That's like Facebook for you old people".

FB is the platform for old friends to reconnect and for extended families to stay in touch - neither of which are that important to a teen. The more interesting trend is teens watching YT in lieu of TV - my teen's viewing habits are almost exclusively centered around YT. It'll be interesting to see what the long-term ramifications of that are.

If true, that would imply that teens will migrate back to Facebook as they get older, but right now I hear them mocking anyone that uses Facebook so much I wonder if they will not use it simply to save face.

I've noticed the same thing regarding TV. Recently we were at a hotel where some of my younger kids were watching TV for basically the first time. They were extremely confused by commercial breaks.

Instagram is still there. Facebook has been declining for a while, all the privacy stuff is just making everyone more aware.