I don't know if other social media sites are necessarily on the down slide, so much as blockchain is genuinely revolutionary, just like Myspace and Friendster we're back in the day. Don't get me wrong, I hate Facebook, but they are building a strong foundation that will be hard to undermine. It might take another 50 years to fail just because it's big, like it did for Sears.
Steemit is great because of the blockchain, not just because of the money it provides. That being said, I'm sure we'll see a resurgence of value over the next year or so, just like we always do with interesting blockchain companies.