Ethereum's Fusaka Upgrade Strengthens Base Layer for Decentralized App Growth

Ethereum’s upcoming Fusaka upgrade, scheduled for activation on the mainnet on December 3, 2025, is set to significantly enhance network scalability and reduce costs for Layer 2 (L2) rollups. The upgrade will implement a phased expansion of blob capacity—the data storage units critical for L2 solutions—alongside the introduction of Peer Data Availability Sampling (PeerDAS) via EIP-7594, which aims to optimize node efficiency and data verification processes . Developers have outlined a structured rollout plan, including testnet deployments starting October 1 on Holesky, followed by Sepolia and Hoodi, to ensure stability before mainnet deployment .

The core objective of Fusaka is to increase Ethereum’s data throughput to support growing L2 adoption. Blob capacity will expand from the current 6/9 target/max to 10/15 blobs per block on December 17, 2025, and further to 14/21 blobs by January 7, 2026. This doubling of capacity is expected to reduce transaction fees for L2 users while enabling higher throughput for applications requiring large data sets, such as rollups and decentralized finance (DeFi) protocols . The phased approach, termed Blob Parameter Only (BPO) forks, allows for incremental adjustments without requiring full client rewrites, minimizing disruption for node operators and developers .

PeerDAS, a key innovation in Fusaka, will reduce the bandwidth and storage demands on validator nodes by enabling data availability sampling. Instead of downloading entire blobs, nodes will verify data through randomized sampling, lowering operational costs and potentially increasing network decentralization by making node operation more accessible to smaller operators . This change aligns with Ethereum’s broader strategy to strengthen its base layer as a scalable settlement infrastructure while supporting L2 growth .

The economic implications of Fusaka are also significant. By increasing blob capacity and optimizing data handling, the upgrade aims to align Ethereum’s revenue model with its role as a settlement layer. Developers are debating proposals like EIP-7623 and EIP-7762 to adjust incentives for blob usage, addressing concerns that high utilization rates (nearing 80%) do not currently translate into proportional revenue for the base layer . Additionally, EIP-7918 will introduce bounded base fees for blob transactions, creating more predictable costs for data-heavy applications and further stabilizing the network’s fee structure .

Fusaka builds on prior upgrades, including the May 2025 Pectra hard fork, which improved staking efficiency and account abstraction. The upgrade also follows the Dencun upgrade (2024), which introduced blobs to reduce L2 costs. With the validator exit queue reaching an all-time high of 2.6 million ETH, the Ethereum community remains focused on balancing scalability with security. Co-founder Vitalik Buterin has emphasized that longer exit times are necessary to maintain network robustness, despite concerns about potential sell pressure from unstaked ETH .

The success of Fusaka will position Ethereum to handle up to 2,000 transactions per second in the long term, as outlined in proposals like EIP-9698, which envisions a 100x gas limit increase. This trajectory supports Ethereum’s vision of becoming a foundational layer for decentralized applications while addressing criticisms of L2 fragmentation. The upgrade’s emphasis on infrastructure improvements, coupled with ongoing efforts like the Open Intents Framework, aims to unify cross-chain experiences and mitigate risks from growing multichain adoption .