Undoubtedly useful for different issues
Within the first state of affairs, Layer-3s can be utilized for custom-made features similar to privateness. The purpose wouldn’t be to offer extra scalability in such a case. The Layer-2 would offer scalability to functions, and a Layer-3 would serve the custom-made performance wanted for various use circumstances.
Within the second imaginative and prescient, the Layer-2 provides general-purpose scaling, and the Layer-3 offers custom-made scaling by way of specialised functions. The Layer-3 would compute knowledge by way of means aside from the EVM or rollups, whose knowledge compression is optimized in response to particular knowledge codecs.
Within the third imaginative and prescient, Layer-3s can present weakly-trusted scaling by way of Validiums, which use SNARKs to confirm computation. Information availability, right here, is the accountability of a trusted third celebration. Buterin mentioned that though Validiums supply a decrease safety grade than rollups, they’re “extremely underrated” and “vastly cheaper.”