Hi @rncd, I think you bring up some good questions around the long-term vision of creating a decentralized metalayer. Such a layer of abstraction appears to consist of the collective sum of all the independent DONs, where each can be constructed to serve a particular use case. A hybrid contract can use the services provided by existing DONs, as well as launch their own DON, to meet their specific requirements. So in my opinion, it seems scaling the metalayer would entail launching additional DONs to provide more services for a larger collection of users.
By extending this definition of oracles, a metalayer really goes beyond data delivery to include any other capabilities that blockchains do not. A DON itself could operate in an entirely autonomous manner, such as reading the mempool for transactions and automatically fulfilling jobs as needed. Each DON could therefore have its own Overseer to change network parameters or automatically process requests using the original deployed design.
On the point about the incentive-based security and FSS, nodes who participate in DONs may provide a wide range of oracle services. I believe these diverse services can be taken into account with Future Fee Opportunity (FFO) within the Implicit Incentive Framework (IIF) where additional cryptoeconomic security is derived from the fees generated from providing oracle services. So the more services a DON node provides, the greater the amount of fees it can generate, leading to greater cryptoeconomic security as a whole. It would be interesting to see this quantified for each specific oracle service a DON could provide.