I feel that you are considering a "hybrid" scenario. This made me think of a project I studied recently.

Currently there are many blockchains, but they all act "isolated", there is no interoperability.

There are several projects that are making interoperability between blockchains real. But there is one that goes beyond and allows interlocking permissionless blockchains with private blockchains. In fact, it also allows interoperability between blockchain - private network, raising the possibility of a hyperconnected future that allows value transactions.

You can know a little more in my post.