In fact, specifically for this reason, it’s forseeable that Mauritius does not retire the domain but keeps .io around, the same way that Russia keeps .su around (.ru being RUssia, and .su being the Soviet Union that hasn’t been around for quite a few decades now).
Some countries make a lot of money from those domain licenses. Some are small enough that it could weaken or destabilize their economy.
In fact, specifically for this reason, it’s forseeable that Mauritius does not retire the domain but keeps .io around, the same way that Russia keeps .su around (.ru being RUssia, and .su being the Soviet Union that hasn’t been around for quite a few decades now).