I would think that such an implementation would go through a period of time available as an external library before it would "qualify" to be added to the core. For that matter, I don't see any big reason to add it to the core at all, other than making things simpler for users...
(but it might be better in general to add some sort of improved library handling to the arduino environment, so that the issue of whether things should be added to "the core" comes up less often...)