Fair enough, I hadn't been keeping track of their pace of development. Doesn't look super active.

I'm operating under the assumption that for a while the bulk of new user growth will happen on the existing larger instances, which are all running Lemmy, rather than Piefed or Mbin instances growing faster than them. I think that'll remain true even once Piefed and Mbin are more featureful than Lemmy, unless the gap is really significant.

If that turns out to be true, then for Lemmy to no longer be the dominant software, the existing big instances would need to switch, which wouldn't be a trivial task. Piefed or Mbin could add the ability to migrate an existing Lemmy database, but I assume that it would be overall easier and less risky for them to move to a Lemmy clone than to a different system.