99% of users rely on that labor. And it isn't a given some other forums will rise to the same level.
This dumb trope of "economics will ensure an equivalent product will appear" is a laissez faire fantasy.
I’m sure it will be similar for Reddit - no clear “winner” at first, but the start of a gradual and irreversible decline for the incumbent.
To my understanding, it would be distributed and virtually independnet from central provider. It would be nice to have something like that for "communities" (slightly different from microblogging or chat/discord)... lemmy seems nice but it's somewhat akin to mastodon where each server is kinda isolated and while you can now federate, searching for communities across the fediverse is not the best experience yet...