The fact that your internal architecture has been built upon a rich cohesive ontology that fits your requirements, and provides for robust and easy to maintain enterprise software need not determine (or compromise!) what you want to publish to any given consumer. Marking up content to a specific schema representing your linked data can be done as a post publication (or post content creation) exercise. Your consumers are thus not coupled to the schema you have used to deliver your internal use cases, just as traditionally your consumers should not be coupled to your relational model. You might have consumers that are happy to accept content that is marked up in conformance with your cohesive domain ontology, however should a consumer ask for it, you can map the content markup to Schema.org via an outbound transformation. The late binding ethics of the REST philosophy still apply.