The reason DBI works is that it doesn't do anything. It provides a API, and a very simple one, at that. Plus, it's working on top of an extremely well-defined (if poorly thought-out) language - SQL. If you don't believe me, think about what it would take to build a DBD for DBM::Deep.

It seems to me that you are getting ahead of yourself. What you really want is a way of standard way of querying configuration, regardless of how it's stored. Define that and you can use DBI as your configuration manager with people providing DBD's for each configuration method.

Good luck.