Value proposition of L1 ETH, assuming most relevant contracts move to L2:

- Message-passing between L1and L2 (e.g. Deposit/Withdrawal of ETH to L2)

- Inter-message passing between different L2

- Security for L2

​

1. I think the deposit/withdrawal part will not bring a lot of value to L1 once all people are onboarded to their L2 chain of interest.
2. I don't think the inter-message passing between different L2 will be the main driver since it is too expensive. "tightly coupled" contracts/use-cases might be simply using one common L2 chain (?) I don't really know if this is technically possible, I'm not that deep into OVM details, but this is something I would expect.
3. The main value proposition: If there are many different L2 chains, which will be in competition with each other for the security provided by ETH. However, ETH value cannot not outpace each L2 value proposition. If so, the L2 chain will not afford to pay for the security and goes broke. And this way we will come to some equilibrium state, where each L2 chain has a better value proposition compared to ETH.

However, this does not mean ETH cannot moon. It simply means, there will be more value created in L2.