The Limits of L2 - Martin Köppelmann - YouTube

In this talk from ETHDenver Martin Köppelmann, the leader for Gnosis, highlights the limits of Layer 2 scaling solutions for Ethereum, and advocates that "side chains" (he doesn't use that term) need to be part of the answer. To me what he describes as Ethereumverse is the obvious path. In this scenario, Ethereum is the shared protocol, and assets and transactions can move on mainnet, layer 2s, and side chains all based on the needs of the specific applications. This is the way.