It would be nice if the pattern were better documented, and perhaps more consistently implemented (and if drivers were more easily extended). It's difficult to see much commonality between the implementation of drivers for the database and for sessions.
I implemented a simple authentication/authorization "driver" system and one to replace the form library for Bonfire (neither of which I ever really got around to integrating into Bonfire). More recently, I implemented a driver system for the library used to convert Markdown/CommonMark documents in Bonfire's docs module.
Almost anything which allows for a (relatively) simple interface, potentially including template libraries, can be implemented like this, it's just a matter of whether it is actually useful for the specific feature and what impact it might have on the overall performance of that feature.
