The social media outlets (Twitter, Facebook) may not be gone, per se, but will not be a big part of society in ten years. Here's why (this is long, and won't have a TLDR, but it's in labeled sections for your convenience):
Viral
"Viral" doesn't really exist anymore. There was a boom with the advent of the internet (think grape-stomping lady-era internet) and with YouTube, and briefly with Vine, but now nothing is natural. Everything from news stations to high school principals to advertisers capitalized on the "going viral" craze by staging events and acting crazy for the camera. Have you watched Tosh.0 recently? Do you recognize anyone he redeems now?
Kids
Kids who are 15 now will be 25 in 10 years. By then, the contemporary users of Facebook and Twitter in their heydays (roughly 2011) will be well into their 30s, to say nothing of the middle-aged adults using at that time. Kids who are 5 now and know their parents to be social media people will be 15 in 10 years, and will probably not want to do things their parents thought was cool at that age.
Adults
Speaking of the older generations, they too will fall victim to time in terms of interest in social media. All the "catching up" that the older generations did with old classmates, etc. has already occurred. There's nothing left for them to do on Facebook other than share articles and organize extramarital affairs (which will decrease as, say, the 50 year olds doing that now will be 60).
Privacy/Oversharing
The idea of "privacy" has taken off recently. I can see people getting away from the idea that they have to post pictures of their children on the internet for all to see, for example. I also foresee a rise in wanting to enjoy the moment, and not messing with filming and sharing it.
Twitter Loses Its Charm
Twitter is about to run its course. For proof of this, I submit to you Rob Delaney. Rob is a very talented guy (his standup is good, as is Catastrophe), and maybe he would have been famous anyway. However, he is famous largely because of his Twitter account. There are other comedians on there that have boosted their fame, but not really to Rob's degree. I don't think we'll see another person "get famous" from Twitter. Further, there are a limited number of ways to make 140 characters funny, which is becoming obvious now (it's turning into the same ALL CAPS or "all lowercase showing apathy" jokes). As we get away from this "outrage culture" (and it's coming soon--these things always move in cycles, and you can see it already on here through the most upvoted comments), the need to post thinkpieces and the like will dissipate.
I would answer the question of where the outlets will be in 2025, but that goes outside the scope of this topic.