The iExec network needs a Domain-Specific chain to track deals between the different actors interacting on its marketplace for cloud resources (buyers and sellers of computing, datasets and applications).
The chain would be used to record all contributions of these actors to trigger payments using PoCo (The iExec Proof-of-Contribution algorithm). For private and consortium use of the iExec Stack, a PoA bridge and chain can be set up to offer an enterprise-ready solution.
For public usage, iExec has more complex requirements and is experimenting with Substrate to tackle: a token-based PoS consensus, governance, upgradability, the use of wasm for new features, and interoperability as a Polkadot parachain.