> but I'm just not convinced the average user is going to switch to decentralized/federated/peer-to-peer social networks.
This is probably true. We could still be using USENET, or at least something built on netnews, but we aren't. I don't know what it would realistically take to get traction into a durably federated system again.
> discoverability is going to be an incredibly difficult
I'm not sure, how are you doing discovery now (and what sort of content are you looking to discover)? I don't really sub to subreddits, so much as I just end up at posts through google searches. That should still function fine. For example, as an owner of a Honda Shadow motorcycle, I didn't have any trouble finding hondashadow.net --- most good quality google results regarding those machines come from there. And given the quality of the content, I eventually decided it would be a good idea to join up. I imagine without reddit/discord/, this type of situation would be common.
On the other hand, if you're looking for a feed aggregator to passively discover interesting new posts, that might be harder. RSS, if built into common forum software, could be leveraged here...
If what you're looking for is a master list of communities to browse/join, USENET had a not unreasonable structure, mostly. But we're back to the federated problem.
> and in any case it's far easier for a user with little technical knowledge to start a subreddit vs starting and maintaining a forum.
This is a sticking point =(
> SEO spam
Add to that the developing situation regarding AI generated soup, and... well, I'm not sure how things will settle, but it definitely throws a wrench into any dreams of paradise.