Old social media sites don't die, they just collapse into small, tight-knit and insular communities. There are still people on Usenet, Livejournal, MySpace, Flickr. Steem is particularly likely to do something like that in its worst case because it's not reliant on being maintained by a single corporation.
you are right about that, the other day someone brought up some stats on myspace and my mind was blown a little bit. As much as we think they are "dead" they have a lot more active users than us... go figure.