Scaling with Layer 2s: Rollups vs Sidechains

This report describes Layer-2 scaling solutions for blockchains, focusing on rollups (optimistic and zero-knowledge) and sidechains, the role and centralization risks of sequencers, security implications of sidechain independence and dependence on Layer-1, and how these technologies affect Layer-1 roadmaps (e.g., EIP-4844 and sharding priorities). It highlights trade-offs between scalability, decentralization, and security, and notes ongoing work to decentralize sequencers and refine fraud-proof mechanisms.