According to the latest article "Different types of layer 2s" on vitalik.eth.limo, the article states that Ethereum's second-layer ecosystem has been expanding rapidly in the past year. The ZK-EVM rollup ecosystem, traditionally featuring StarkNet, Arbitrum, Optimism, and Scroll, has developed rapidly and made great progress in improving security. One of the inevitable results is that second-layer projects tend to become more heterogeneous.
This trend is expected to continue for the following reasons: 1. Some projects that are currently independent of Layer 1 are seeking to get closer to the Ethereum ecosystem and potentially become Layer 2. These projects may need to transition gradually. Switching all at once now would result in decreased usability because the technology is not yet ready to bring everything together. 2. Some centralized projects want to provide more security guarantees to users and are exploring blockchain-based avenues to achieve this goal. In many cases, these projects would have explored "permissioned alliance chains" in previous eras. 3. Non-financial applications (such as games or social media) want to be decentralized but only require a moderate level of security.
