I don't know if a federation really solves the issues you’re concerned about. In all likelihood, singular entities will still be operating federations; the keys will just be distributed to people within them. On a local/community basis, federations are great, but Cashu also works since there’s a social risk to operating a mint, and many mints can spring up. MPPs also make the centralization of Cashu mints less of an issue; I’d rather trust several completely unrelated mints than a single federated one.