Adding onto that, the quality of Reddit content [in my former subreddits] has slid dramatically in my opinion. Sure, those niche communities will exist and persist for a while. But, as more tech pros move to the Fediverse I have to imagine that is where a lot of information will reside going forward. Hopefully it becomes or remains discoverable. I get some glimmers of this happening with the various Steam Deck communities here. It is already happening with the various programming communities.

I think a far more likely thing to happen is that you get people scrapping the Fediverse for content to repost on Reddit, like what happens with Facebook and Instagram users scraping TikTok for content to repost. Social networks these days seem surprisingly sticky now that it isn't just a place where all your friends are at.