Personally I think we've hit a point where the novelty of social networks is starting to wear off, and people are starting to realize that they don't actually control the data they're putting out on the internet. I'd much rather use a platform like Steem, where all the data is public domain, than letting some huge business control that data and potentially manipulate it.

A more grass-roots approach, allowing anyone to build their own social network (whether a forum or reddit platform) is what I imagine the next big thing to be.