How can I show the drop-down lists for countries/administrative areas (from Addressfield) as exposed filters in Views? When editing the values of addresses provided by the Addressfield module, selecting certain countries (e.g., the United States) automatically populates a drop-down list of states.

I would like to do the same thing in a View using exposed filters-- when a user selects a country using the exposed filter for country, it should make available a select box for administrative area (state/province).

Adding exposed filters for the country and administrative area do not generate drop-down lists; instead, I simply get a plain text field with the standard options- is, contains, etc.

By installing the Countries module, I can get a drop-down list of the countries (but not the administrative areas).  How can I do this using only the Addressfield module?

Is there a pre-existing solution to make it work like it does on the edit page?
As of right now, there is no such views integration in the Addressfield module, although the linked issue does include a discussion of possible directions to take to tackle the problem.