"objects should be a bit more decoupled from their state"

Do you mean allowing the "class" of an object to be changed - CLOS can do that. Mind you it's a long time since I wrote any code using CLOS and even then I'm pretty sure I never used change-class.

The thing I'm envisioning is something akin to typeclass instances / trait impls, but specialised to the case where you have a service with identity rather than being for general function implementation. Just making the bridge between the "bag of state" piece and the "interface implementation accessible via a name/reference" piece a bit more of a first-class citizen.