Importantly, reddit allows the creation of microforums. Not everyone has the time, energy or ability to build out a full site with a complete forum to make it worth everyone's while. I see Facebook & Discord taking Reddit's piece of the pie in the short term.
Personally I don't see a significant portion of the Reddit user base leaving over this. Basically every major and minor city in the USA has its own subreddit. How many of those users are really going to leave and switch back to Facebook groups?
