Researchers from several institutes worldwide recently developed Quarks, a new, decentralized messaging network based on blockchain technology. Their proposed system could overcome the limitations of most commonly used messaging platforms, allowing users to retain control over their personal data and other information they share online.
I disagree here. with p2p/federated you have to worry about if your microprovider goes out. I think blockchain would be a useful way to keep a users preferences and to keep usernames distinct.