The quality of discussion on Reddit will also suffer. They may actually gain new users from all the media attention they’ve been getting, but I can already tell that some of the subreddits I frequented have seen some of the best members leave and more people more obsessed with fitting in / upvotes and trolls shitposting. It doesn’t take much for a niche sub with, say, 5k users of which 200 are really engaged with the sub, to change for worse once those people start coming in.
I had no idea Threads was a thing until the last few days, and everything I’ve read since there makes me think it’s kind of a pathetic half assed effort like Google+, but awfully desperate to try to get people to like it and pay attention.