I would fully expect this trend to continue - each new generational cohort will latch onto a new social network that is separate from the ones their lame parent

I would fully expect this trend to continue - each new generational cohort will latch onto a new social network that is separate from the ones their lame parents and older siblings use. This poses a massive institutional risk to any social network. They either need to aggressively pump out new brands to try and capture that themselves, or buy promising startups, but it wouldn't be too difficult to fail at both of those and just completely skip a generation. A few of those misses added up could be a terminal failure.