Keeping everyone happy and not causing major diplomatic incidents. Uh-oh.
Yup. Now that you've mentioned the Falklands - those should sort under "M" (for "Malvinas"), everyone* knows that, right? Don't get me started on that farce of a name that hides under the acronym FYROM, either. And, btw, some existing and recognized countries have an ISO-3166 shortname which its populace mostly considers offensive ("Czechia"). Yeah. Easy peasy.
Not to mention the previous half-baked browser-specific solutions such as input=date...nope, I don't have any hope for this proposal.
(Everyone in Argentina, that is.)