Are servers hosted on fediverse open to being indexed by search engines otherwise I doubt it can replace reddit. Reddit did discussion threads , subs, and searchable results from search engines really well. It was a really great version of "forums" . I am not sure fediverse or Discord can do such things.
I was very sad too when it finished. But I think it had one of the best runs and ending possible. I wouldnt have wanted it any other way.
One thing I loved about that era of computing is that it was possible to know the whole computer from the bottom up. I dont think it will now ever be possible.