That just means the fork would also need to be AGPL licensed, and the owner of the fork wouldn't be able to also sell a proprietary version with additional "enterprise" features. And IMO that would be a good thing.

I think it is unlikely a single entity would do that. But a coalition of current MinIO users might get together to create such a project, perhaps under the Auspices of a foundation such as the Linux Foundation. Although, I think that scenario would be more similar to OpenTofu than Valkey.