this is an interesting question i’ve had banging around in my mind since well before Reddit’s implosion (and Discord’s enshittification), but which seems really worth asking now.
you can’t blame Reddit and Discord or their imitators entirely for these going out of style, but they’ve sure put the dagger in a lot of remaining ones, and i kind of wonder if they’re just in an irreversible and terminal decline a la USENET. i can only name two or three i even consider checking anymore, and i’m not sure how sustainable any of those are long-term.
I think no, but not because of the growth of the internet, but rather the reluctance of change within forums. I used to be a member of a Disney forum and the userbase became quite toxic and echo-chambery. With stuff like discord and reddit, its easy to just create a new subreddit/discord to join if the mods and userbase of the main sub/discord become bad. Not so much with forums.