On: Taking control of all .io domains with a targeted ...

[Symbiote]

When Britain (and thus the US) decide they no longer require the island for a naval base, it will be given to Mauritius.

The .IO domain would eventually be deleted, and that territory represented under the existing .MU (Mauritius) domain.

Judging by https://en.wikipedia.org/wiki/.mu I don't think the Mauritian people have much benefit from the arrangements for .MU.

[vertex-four → Symbiote]

.SU - for the Soviet Union - still exists, I somewhat doubt that many TLDs will ever be deleted in general.

[kijeda → vertex-four]

.SU is actually the only former country with a TLD still delegated, and quite a few have been removed. In recent years .AN, .TP, .YU, .ZR have been phased out representing former countries.