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.
Colonize is not the same as terraform.
Mars could be colonized without terraforming it. Closed habitats could be permanent thus providing a way of colonization.
Terraforming is a trouble without magnetosphere that’s true. But not impossible. As there are tech concepts on how it could be possible to shield mars atmosphere. And doesn’t seem imposible, just expensive and complex.