Why Permissionless Sequencing is the Ultimate Goal

A single entity controls transaction ordering and inclusion, enabling MEV extraction and compliance-driven censorship. This directly contradicts the credibly neutral settlement guarantee of Ethereum L1.

• Centralized Risk: A single sequencer failure halts the chain.
• MEV Capture: The sequencer can front-run user transactions for profit.
• Regulatory Pressure: Can be forced to censor addresses.

Permissioned sequencers capture the full economic surplus from transaction ordering, creating a multi-billion dollar rent extracted from users and builders. This is value that should accrue to validators or be returned to users.

• Value Leakage: MEV revenue is captured by a single entity, not the network.
• Inefficient Pricing: Users pay for security but get a weaker, centralized product.
• Stifled Innovation: Builder and searcher ecosystems are neutered.

Centralized sequencers run on cloud providers, creating systemic risk. An AWS region outage can take down a major L2, breaking the core blockchain promise of uptime and decentralization.

• Infrastructure Risk: Single cloud provider dependency.
• ~30s+ Finality Delay: Users must wait for L1 challenge periods for real security.
• Weak Credible Neutrality: The chain's operation is trust-dependent.

Espresso provides a decentralized sequencer network that multiple rollups can plug into, creating a shared, high-throughput mempool. This enables cross-rollup atomic composability and MEV redistribution.

• Enables atomic cross-rollup bundles for protocols like UniswapX.
• Redistributes sequencer profits via a DAO-managed treasury.
• Integrates with EigenLayer for cryptoeconomic security.

Astria offers a no-code stack to launch a rollup in minutes, backed by a decentralized sequencer network. It decouples execution, sequencing, and data availability.

• Eliminates the 'sequencer key' problem for new chains.
• Uses Celestia for data availability, minimizing costs.
• Provides fast, soft-confirmations before settlement to L1.

Today, every major rollup (Arbitrum, Optimism, zkSync) uses a single, permissioned sequencer. This creates censorship risk, high latency for L1 escape hatches, and captures all MEV.

• Censorship vector: A single entity can reorder or exclude transactions.
• L1 withdrawal delay: Users must wait 7 days to bypass a faulty sequencer.
• MEV capture: $100M+ annually in extracted value flows to a single entity.

Permissionless sequencing turns block production into a competitive auction, similar to Ethereum's block builder market post-PBS. Rollups auction the right to sequence blocks to the highest bidder or most performant network.

• Drives down costs via competition among sequencer providers.
• Unlocks native cross-rollup liquidity through shared sequencing layers.
• Aligns incentives by allowing users/stakers to share in sequencer revenue.

Radius solves the sequencer centralization problem from a different angle: it uses practical verifiable delay encryption (PVDE) to create a private mempool. Sequencers commit to blocks without seeing transaction content first.

• Eliminates frontrunning and reduces toxic MEV at the source.
• Enables permissionless participation in sequencing.
• Preserves composability while hiding transaction intent.

The final stage separates settlement from sequencing. Rollups become sovereign, posting data to a DA layer like Celestia or EigenDA and using a permissionless sequencer set. L1s like Ethereum become high-security courts, not daily operators.

• Maximizes sovereignty: Rollup logic is enforced by its users, not a parent chain.
• Minimizes cost: No expensive L1 execution fees for validation.
• Exemplified by projects like Dymension RollApps and the Celestia ecosystem.

Permissionless sequencing risks recreating the validator centralization it aims to solve. A small group of sophisticated actors could dominate the sequencing market, extracting value from users and creating new trust assumptions.

• Economic Capture: Top sequencers could form a cartel to censor or front-run transactions.
• Staking Centralization: High-performance requirements may lead to <10 entities controlling the majority of stake, mirroring L1 validator sets.

Fast block times and high throughput require low-latency communication between geographically distributed sequencers, a fundamental conflict with decentralization.

• Network Physics: Achieving sub-second finality likely requires centralized server clusters, defeating the purpose.
• Protocol Bloat: Solutions like Dymension's RDK or Espresso Systems add complexity, increasing the attack surface and time-to-market.

Sequencer revenue must cover high operational costs (hardware, bandwidth) and provide sufficient staking rewards to secure the network, a difficult equation.

• Fee Market Collapse: In a competitive market, sequencing fees could be driven to near-zero, undermining security.
• Subsidy Reliance: Many projects like Astria or Radius may require prolonged token inflation or VC subsidies to bootstrap, creating sell pressure.

The ecosystem risks splintering into incompatible shared sequencer networks (EigenLayer, Espresso, Astria), creating liquidity silos and defeating interoperability goals.

• Rollup Lock-In: Rollups may get vendor-locked to a specific sequencer set, reducing optionality.
• Cross-Domain MEV Complexity: Extracting value across Ethereum, Celestia, and Avalanche requires fragile bridging, a problem Across Protocol and LayerZero already struggle with.

A truly permissionless sequencer network is a regulator's nightmare: an unstoppable, anonymous transaction ordering service.

• OFAC Compliance: Networks could be forced to implement transaction censorship, violating neutrality.
• Legal Liability: Sequencer operators may face securities law exposure for ordering profitable MEV bundles, chilling participation.

End-users prioritize low fees and fast transactions, not ideological purity. Centralized sequencers from OP Stack or Arbitrum may simply be 'good enough'.

• Adoption Friction: Explaining the benefits of permissionless sequencing to a normie is a go-to-market hurdle.
• Performance Parity: If Coinbase's Base offers $0.01 fees and 2s finality, the marginal benefit of decentralization is a hard sell.