Frozen enums are a major drag for making frameworks that are just used internally by a single app as a way to avoid code tangle in the app by making it modular. The contortions required because extending enums isn't possible in this context are painful.
If this proposal makes that possible I'm +100 (inflation!).
Though (catching up) reading Enum cases as protocol witnesses - #20 by sveinhal , it uses a protocol to define common enum cases which can then be "extended" in concrete enum definitions that conform to the protocol which might actually solve our use case more cleanly.