The accepted PEP states that the frame hack should be removed: "To support pickling of these enums, the module name can be specified using the module keyword-only argument."

Ergo, if you don't specify it, they cannot be pickled. Explicit is better than implicit, and this hack should not propagate beyond namedtuple (it should actually be deprecated in namedtuple as well).

As far as the second point goes, I had already reviewed the PEP implementation before making the comment (that's why I am reasonably sure you can already do it just by overriding _get_mixins). I see it as similar to the changes that were already made to support autonumbered subtypes.

However, also note that I said we should wait before doing anything about providing a supported mechanism for that customisation. I've now created issue 17954 to cover a possible refactoring and documentation of that part of the implementation.