Still, I'm not sure using references in the crypto data itself is a good thing. You will get more requests, more infrastructure dependency, more metadata tracking, for fixing the bloat of a minor (in size) part of the protocol, and getting cryptographic agility, that is a disagreeable feature at best.

Also, once they have references, why are they adding polymorphism too? Polymorphism is a hack that tries (but fails) to solve the same problem.