On the topic of social media in decline, TikTok also appears to have peaked in content already. Following people isn't that interesting since most content creators that hit it big are One Hit Wonders. After they hit that big growth spike, they either follow the herd with the latest dance or trend, or they keep doing the same thing that made em famous with slight variations. How long can you milk the same dance routin…
You have to commend YouTube and Twitter's longevity as social networks. YouTube has better and more content than ever. Twitter also has the best and most relevant content, provided you curate your feed. All the stuff happening on academic Twitter, for instance, is hard to find elsewhere. Reddit also seems to be going down the path of irrelevancy. The content is increasingly mediocre and hivemind-ish.
Nope, frankly given how long reddit's been around and how it continues to gain in popularity I expect it will outlive everything on that list except for youtube. It's the webs default forum and there will always be a demand for a forum on the web.