> It should eventually get removed by ICANN, since the country code TLDs are managed by ISO 3166-1 alpha 2 (it's however not an exact match), and the transfer will mean the British Indian Ocean Territories will no longer exist. ISO is going to be the entity in charge of removing the io country code, which it probably will do since ISO 3166-1 alpha 2 isn't just used for domain names.

Side note: I suspect the real reason Google wants to discontinue goo.gl links is because they believe Trump will eventually succeed in annexing Greenland to the US.