For this I neither like the idea of baking in a single user (writer) interface from the start, nor committing to a particular database format.
This database driven design is mostly for bigger companies, and it’s quite likely they already have some other PCB design suite and an elaborate database with their preferred parts in place.
So I agree wit retiredfeline to define an agnostic interface combined with some reference implementation.
Also, as an Open Source project, there are already a lot of side projects around KiCad. It’s quite likely that if there is a definition for a good interface and a reference implementation is made, that interfaces to other databases will also be released over time.