Vitalik Buterin, Ethereum co-founder, believes layer-3 solutions will provide “customized functionality”. He said a third layer on the blockchain makes sense only if it provides a different function to layer-2 solutions. It should be noted that layer-2 solutions have been focused on hyperscaling the network.
Buterin outlined that a three-layer scaling architecture that consists of stacking the same scaling scheme on top of itself generally does not work well. He said rollups on top of rollups, where the two layers of rollups use the same technology, certainly do not. The Ethereum boss pointed out that a three-layer architecture where the second layer and third layer have different purposes, but can work together.
One of the use cases would be customized functionality – privacy-based applications that would utilize zk proofs to submit privacy-preserving transactions to layer 2. Another application would be customized scaling for specialized applications that don’t want to use the Ethereum Virtual Machine (EVM) to do computation. Buterin said layer 3 could be used for weakly-trusted scaling through Validiums, a zk-proof technology. It may be beneficial for enterprise blockchain applications by using a centralized server that runs a validium prover and regularly commits hashes to the chain.
However, it’s still unclear whether layer-3 structures will be more efficient than the current layer-2 model when it comes to building customized applications on Ethereum. Buterin said a three-layer model allows an entire sub-ecosystem to exist within a single rollup, which allows cross-domain operations within that ecosystem to happen very cheaply without needing to go through the expensive layer-1. But building layer-3s may not necessarily improve the efficiency of the network because cross-chain transactions can be executed easily and cheaply between two layer 2s that have committed to the same chain.