Ethereum Layer 2 solutions, designed to scale the network by processing transactions off-chain, may inadvertently reduce mainchain activity over time. As L2s offer faster, cheaper transactions, users and dApps could increasingly favor them, diverting traffic from the mainchain. This shift risks lowering mainchain usage, potentially impacting validator rewards and network security, as fewer transactions occur on Layer 1. However, the mainchain remains critical for L2 security and final settlement, ensuring its relevance. While L2s could "erode" mainchain activity by capturing routine transactions, Ethereum's roadmap, including sharding and rollup-centric designs, aims to balance this dynamic, maintaining mainchain vitality. Long-term, the interplay between L1 and L2 will likely stabilize, with each serving distinct roles.