Dencun Upgrade: Two Years of Practice—Has Ethereum Truly Fulfilled Its Promises?

Since the Ethereum mainnet launched the Cancun-Deneb (Dencun) upgrade on March 13, 2024, nearly two years have been enough to test the actual effects of this reform. This is not just a routine technical iteration but a deep innovation by Ethereum to achieve scalability—centered around the Proto-Danksharding technology introduced by the EIP-4844 proposal. Looking back, how has this upgrade truly changed the landscape of the Ethereum ecosystem?

From Proto-Danksharding to “blobs”: understanding the core technology of Dencun

The most significant breakthrough of the Dencun upgrade is the introduction of the “blobs” (block data) concept via EIP-4844. Rather than a sudden leap in technology, this is a phased step toward full Danksharding—a carefully designed transitional stage.

Previously, Ethereum transaction data was permanently stored on the blockchain, leading to rising storage costs. Proto-Danksharding changed this logic: it allows transaction data to exist as temporary “blobs” (each slot with 1MB capacity), which do not need permanent storage and can be short-term circulated among validator nodes. This seemingly subtle design has profound implications—especially for Layer-2 solutions.

Layer-2 networks (such as Arbitrum, Optimism, Polygon) rely on periodically submitting transaction proofs back to the Ethereum mainnet. Before Dencun, the cost of submitting these proofs accounted for 50-80% of total Layer-2 expenses. With the introduction of blobs, this cost is significantly reduced—potentially by 10 to 100 times.

Beyond Dencun: five additional optimizations—comprehensive upgrade list

In addition to Proto-Danksharding via EIP-4844, the Dencun upgrade includes four other major improvements, forming a multi-dimensional optimization system:

EIP-1153 introduces temporary storage operation codes, allowing smart contracts to use cheaper temporary storage during execution without relying on expensive permanent storage. This is especially friendly to complex DeFi applications and can directly reduce gas costs.

EIP-4788 improves interaction between consensus and execution layers by fixing the Beacon Block Root, enabling the execution layer to access consensus data directly. While this seems like a technical detail, it lays the foundation for future cross-layer interoperability.

EIP-5656 adds the MCOPY operation code, providing a more efficient way to copy memory data, further optimizing contract execution efficiency.

EIP-6780 restricts the use of the SELFDESTRUCT opcode, a security-oriented improvement to prevent certain low-cost attack vectors.

This suite of upgrades reflects Ethereum’s philosophy—not merely pursuing “speed” or “cheapness” but seeking a balance among security, usability, and scalability.

Practical impact of Dencun: data after two years

Promises in theory often differ from real-world performance. Let’s look at the actual situation after Dencun:

Real changes in Layer-2 costs: Before the upgrade, data from L2fees platform shows that the average cost of transferring ETH on Arbitrum, Optimism, and Polygon was $0.24, $0.47, and $0.78 respectively. Post-upgrade, these costs have indeed decreased—though not by the full 10-100x, a 30-70% reduction is already significant. During low network load periods, fees can even drop to a few cents.

Minor changes in mainnet gas fees: Unlike the substantial improvements in Layer-2, Ethereum mainnet gas fees are influenced by many factors, and Dencun’s direct impact is limited. However, in the long term, Dencun paves the way for future scalability improvements.

Shift in ecosystem activity: The upgrade has spurred developers to reinvest in Layer-2. Many new projects prioritize deployment on Arbitrum or Optimism rather than waiting for natural mainnet cost reductions.

How Dencun reshapes the Layer-2 ecosystem

Layer-2 solutions were originally a stopgap to bypass mainnet congestion, but Dencun has transformed them into more competitive long-term architectures.

A turning point in economics: Fidelity’s research reports that Layer-2 networks accounted for about 10% of total mainnet costs before the upgrade. While this ratio has not drastically changed, the cost structure has fundamentally shifted—from “high-cost solutions” to “highly efficient solutions.” This makes many applications previously unfeasible on-chain now possible.

New application scenarios: The blobs mechanism in Dencun opens new avenues for Data Availability (DA) layer development. Projects like Celestia, EigenDA, and Avail, which specialize in DA, now have new competitive space. They no longer need to rely solely on Ethereum’s storage capacity but can complement Dencun’s capabilities.

Validator and node load: Although blobs do not require permanent storage, they still need validators to temporarily store and process them. During high load periods, this can occasionally cause memory pressure, prompting some community members to call for fine-tuning blob capacity.

Security concerns: the “shadow side” of the Dencun upgrade

Every upgrade carries risks. Dencun is no exception:

Ongoing compatibility adjustments: In the initial phase, some older smart contracts exhibited unexpected behavior with new opcodes. Most issues have been resolved, but this underscores the need for continuous review and testing by developers.

Operational burden on nodes: The introduction of blobs increases disk I/O demands on validator nodes. Running full nodes becomes slightly more demanding, though not enough to threaten decentralization, it warrants attention.

New data availability challenges: While blobs are processed in the short term, not all validators are required to store them permanently. In extreme scenarios (such as large-scale node offline events), data recovery could become difficult.

The Ethereum 2.0 roadmap in perspective: Dencun as a prelude

Dencun is not an isolated upgrade but a key step toward Ethereum 2.0. Reviewing the entire evolution:

Phase 0: Beacon Chain (launched December 2020) introduced Proof of Stake consensus, laying the foundation for modern Ethereum.

The Merge (September 15, 2022) merged the mainnet with the Beacon Chain, achieving a historic shift from PoW to PoS, reducing energy consumption by over 99.5%.

Shanghai/Capella upgrade (April 2023) enabled ETH staking withdrawals, boosting market participation.

Dencun upgrade (March 13, 2024) introduced Proto-Danksharding, laying the groundwork for horizontal scalability.

Petra (Electra + Prague) is in preparation, planning to introduce innovations like Verkle Trees to further optimize storage.

Full Danksharding: the ultimate goal still on the horizon

The “Proto” prefix in Proto-Danksharding is not just a name—it’s a stepping stone toward full Danksharding. Full Danksharding would partition Ethereum into 64 or more shards, each capable of processing transactions independently. Theoretically, this could boost Ethereum’s throughput from the current 15 TPS to over 1000 TPS.

However, implementing full Danksharding is far more complex. It requires:

• More sophisticated cross-shard communication mechanisms
• New validator randomization algorithms
• A completely new security model

Based on current development progress, mainnet deployment of full Danksharding is expected around 2027-2028, rather than the optimistic 2025 estimate.

The Ethereum ecosystem after Dencun: a 2026 outlook

Two years from now, the benefits of Dencun are gradually manifesting:

• Layer-2 maturity: Networks like Arbitrum and Optimism have developed robust DeFi ecosystems, with daily active users surpassing millions.
• Cross-chain bridging improvements: Lower costs facilitate capital flow between mainnet and Layer-2.
• Emergence of new applications: High-frequency trading, on-chain gaming, and NFT trading are flourishing on Layer-2.

At the same time, challenges remain:

• MEV (Miner Extractable Value) issues persist in Layer-2 and can be even more complex in some scenarios.
• Gas costs, while lower, have not reached the ideal below $0.001.
• Centralized sequencers still pose risks in some Layer-2 solutions.

Conclusion: upgrades are just the beginning; the future requires ongoing effort

The Dencun upgrade has fulfilled its core promise—significantly reducing Layer-2 data availability costs through Proto-Danksharding and EIP-4844, bringing tangible economic benefits to the Ethereum ecosystem. It is not a revolutionary breakthrough but a steady step forward.

From a broader perspective, Dencun marks Ethereum’s shift from “rapid expansion” to “sustainable scalability.” It demonstrates that the Ethereum community can achieve ambitious scaling goals through modular design and phased implementation.

With subsequent upgrades like Verkle Trees and full Danksharding on the horizon, Ethereum is building a long-term, sustainable scalability architecture. For traders, developers, and users, the true value of Dencun lies in the possibilities it opens—a future with cheaper, faster, and more versatile Ethereum ecosystem is taking shape.