As a follow-up to heyrocker's great core conversations talk I'd like to share my thoughts on that topic. So is X content? Or configuration? As heyrocker pointed out: We shouldn't have to care.
So yes, the line between content and configuration is blurry - stuff being content on a site, would more fit the configuration bill on another site. Still this doesn't mean we have to treat content and configuration exactly the same way. We can and we need to build separate systems for configuration management and content deployment, but the point is: We need one and the same type of objects to be able to behave as content and configuration dependent on the actual requirements of the site. Not necessarily out-of-the box, but well, it should be doable such that people can implement their use-cases. To facilitate that, we need a foundational unified API, an API that deals with objects the same way regardless whether its configuration or content, an API that allows us to fetch any object, to export it, and to import and save it on another site.
As said in the core conversation, I think the entity API perfectly fits into that. That way, an entity would be basically any data object which is integrated into Drupal, such we have a unified CRUD API - and a unified way to import and export that data. It should be able to deal with machine names or auto-incremented numeric id, but as well we might want it to be able to deal with UUIDs out of the box. So we'd finally get a unified data API and exportability, the very much foundation for solving the configuration management and content deployment problems.
But for that to take off, we need to keep the entity concept slim and don't bake too much assumptions into it. Is it content or configuration? Is it user-facing? Is it fieldable or viewable/renderable? Well maybe, maybe not. So while it makes a lot of sense to build more APIs around entities, we should never actually require them. Instead, we could just provide the APIs such that any entity type is able to opt-in, if it fits the bill.
In addition to that, I'd like to share my thoughts on how the Entity API could help us to cover 2 more points Dries mentioned in his key-note: Web services, and information integration. I'll come back to that in a follow-up post.