Ethereum's future may face challenges from Rollup fragmentation impacting mainnet activity. As Layer 2 Rollups scale, they handle most transactions off-chain, potentially reducing mainnet usage to mere settlement and data availability. This could lower mainnet gas fees and validator rewards, discouraging participation. Fragmentation across Rollups may also split liquidity and user bases, weakening network effects. However, solutions like Rollup coordination, shared sequencing, or interoperability protocols could mitigate this. Ethereum's robust ecosystem and ongoing upgrades, such as sharding, may sustain mainnet relevance by enhancing scalability and data capacity. While fragmentation poses risks, Ethereum's adaptability suggests mainnet activity can remain vibrant if these challenges are addressed effectively.