1. Privacy. Public-by-default needs to go away eventually.

2. Fracturing of the protocol. Permissionless is great, until no one is willing to adopt one another's standards and you lose interoperability.

3. Capture. Large relays and vertically-integrated clients are the lazy way to get good UX. But shortcuts increase centralization risk. And that's if a large entity doesn't Extend Embrace Extinguish the protocol.