https://kbin.social is a great alternative from what I can see. https://kbin.social/m/apple is already thriving, as is https://kbin.social/m/programming
There were 2 posts in the last 24 hours. It's not thriving by any measure.
In fact, you can even interact with communities hosted on a Lemmy instance from a Mastodon instance, or Misskey. Heck, probably Pixelfed, though I haven't checked. Such is the beauty of the fediverse and protocols over platforms.
I quite like the term 'Threadiverse' that's been going around lately.
Content on instances can disappear at a moment's notice if it goes down. My favorite part about reddit is the amount of information it has that is well-indexed by google.
These Lemmy and kbin alternatives might fulfill the moment-to-moment chatter, but it worries me that there's no guarantee of continuity for information. The best you can do is be discerning about the instance you pick. If there was a mechanism for distributing information across instances so it's saved, or some other assurance it'd make me happier about it.
Until identity transcends instances (shared identity databases between all the fediverse), communities are portable, and data peered across mirrors/nodes, it won’t work in a way that promotes longevity.
The fediverse in its current incarnation benefits those that use social media more like a chat room than a wiki. But losing your account to the entire fediverse when an instance goes down seems way worse than an unused community disappearing. It’s like taking an email address from an email host that spun up yesterday for fun, and hoping you’ll keep access to it.