Meta taking their ball and going home some time a ways down the road is much less an issue than them dominating content by being there in the first place. They will have their own moderation and content rules that will shape the content that flows out from them, which will shape each community that interacts with it. Considering the very mercenary approach they have to that, it means that content will be far more monetized and monetizable. Which means both sanitization and pandering, neither of which benefits freedom of thought and discussion.
Considering the huge influx of people coming to places like Lemmy or Kbin to escape that kind of situation (reddit), it may mean the death of the community that has grown so far, before Meta even considers leaving.