I don’t see the lemmy model failing. So, as others, I think is more of a solution in search for a problem.
In general I don’t see any reason to leave Lemmy right now.
Also I don’t think things will keep simple with that model. I see a lot of underlying complexities that the current formula does not have.
Maybe it would be a better to try that model on a fediverse area with less success than lemmy.
Peertube is really struggling for instance. Not really on the developer side of things but on the content creators. Maybe a coop of content creators for peertube could me something that is needed on the fediverse.