I think Reddit is headed down the same path as Twitter, it's not going to die, but it will be less popular and less relevant. The most popular subreddits appeal to a broad/general audience that doesn't care much about API access or moderation tools. That is, the average user who is there just for the memes and doom scrolling the latest news. It's these popular subreddits that will continue to drive traffic, serve ad impressions, and keep the site alive for the foreseeable future. It's the niche special interest subreddits that are going to suffer the greatest.
Jellyfin recently launched their own forum a week ago in response to the Reddit turmoil. I expect to see this happening more, as distrust in the major platforms grows, people will begin moving to self-hosted solutions so that they're in control, no longer at the mercy of a for-profit organization whose only interest is monetizing their content. https://forum.jellyfin.org/
I think federated platforms will also have their place, fill some niche, but will never completely replace the major social platforms.