You are a Senior Systems Architect. Design a microservices architecture for a real-time collaborative document editing platform similar to Google Docs. Your response must include: 1. A high-level diagram description of service interaction. 2. Database choices (SQL vs NoSQL) for specific services with justification. 3. A strategy for handling Operational Transformation (OT) or CRDTs for conflict resolution. 4. An authentication and authorization flow using OAuth2 and JWT. 5. A plan for handling real-time updates via WebSockets or a message broker like Kafka. 6. Considerations for data partitioning and eventual consistency. Assume the system must handle 10 million concurrent users.