Ethereum's Layer 2 solutions, like rollups and sidechains, significantly enhance scalability by processing transactions off-chain while leveraging the main chain's security. They offer lower fees and faster confirmations, making them ideal for high-volume applications like DeFi and NFTs. However, they can't fully replace main chain transactions. Mainnet remains critical for high-value transfers, ultimate security, and decentralized governance, as Layer 2 inherits its trustlessness from Ethereum's base layer. Some trade-offs, like potential data availability issues in optimistic rollups or centralization risks in certain sidechains, limit Layer 2's ability to supplant the main chain entirely. Hybrid approaches, where users choose between Layer 1 and Layer 2 based on needs, are more practical.