While there are still a few ccTLDs that is still being run by registries based outside the region, I think that decision making process should remain with the respective countries. So such situation described above is a bottleneck that needs to be avoided at ICANN level; .NGR for instance should not be run under the GNSO. If the 3 letter TLD is to be opened as gTLD then it would be preferred to reserve the corresponding country codes for ccTLDs. I would expect that necessary processes will be put in place to ensure that the alpha-3 reserved in the 3 letter TLDs are operated in similar manner used by the alpha-2 (both at operation and policy level).

That said, there is still the question of whether current ccTLD registries will be willing to maintain an extra tld. Nevertheless, i think it should be done in the interest of avoiding ambiguity, ensuring clarity and proper structure; It will be good for ICANN to ensure that a country alpha-3 code does not get delegated to an "unauthorised" registry. I fear the future politics within ICANN will be more complicated than we know it if that is not done.

Regards