While the absolute numbers of users that make the switch will probably be small for the foreseeable future, I still think they will make an impact. On Reddit, more than 90% of users never contribute anything. Those will stay there and keep making up the big numbers. But the users that migrate to the fediverse were the ones that posted, commented, moderated and voted on Reddit. If even a small percentage of those leave, it will have a fast greater impact on Reddit than the mere user numbers suggest.
While the absolute numbers of users that make the switch will probably be small for the foreseeable future, I still think they will make an impact. On Reddit, more than 90% of users never contribute anything. Those will stay there and keep making up the big numbers. But the users that migrate to the fediverse were the ones that posted, commented, moderated and voted on Reddit. If even a small percentage of those leave, it will have a fast greater impact on Reddit than the mere user numbers suggest.