Odds are that very few people would notice it (the "obscurity" part). If it's a requirement that such features absolutely cannot be invoke by end users in adva

Odds are that very few people would notice it (the "obscurity" part). If it's a requirement that such features absolutely cannot be invoke by end users in advance of release, it seems like you could always use access control or feature toggles in front of the new backend API. It's important to be aware of such a requirement, but I don't think the fact that some use cases have this requirement gets in the way of "Keystone Interface" as a concept.