A deep analysis of the technical and political challenges surrounding social media interoperability and content schema standardisation. Traces the history of standards efforts from RSS/Atom and Dublin Core through to ActivityPub and AT Protocol, examining what a minimal interoperable content schema would require. Covers foundational metadata needs, content type classification, moderation metadata challenges, and extensibility mechanisms. Evaluates three governance models (open standards bodies like W3C/IETF, consortium-based, and vendor-led) with their respective trade-offs. Concludes with six practical steps toward convergence, including building on Activity Streams 2.0, standardising moderation metadata under EU DSA pressure, and adopting formal extension mechanisms. Frames interoperability as both a technical and political challenge that will determine whether the social web becomes more open or more fragmented.