Stand-ins should be orthogonal to the YANG model

[cabo]

Given the somewhat ossified nature of YANG models, it would severely hinder deployment if a model had to adopt stand-ins before they can be used.
I'd propose to leave the whole concept out of the modeling level -- the model also doesn't say whether the encoding is to be JSON or CBOR, so why would it say something about stand-ins in CBOR.

Of course, once models get stand-in aware, they might want to make optimizations for if stand-ins are in use.
But this could be done in a second step.