Since ipv6 is just a 128-address, you could say any unique national ID is already an assigned ipv6. Heck, if you assign your services a UUID, you have also already assigned them an ipv6.

What makes an ipv6 useful is that you can route to it. Since you will never be connected to the network. The network will never be able to route packets to you, making the whole thing a little pointless.

We're not routable yet. Fairly certain people are trying to create computer/brain interfaces...

I'm thinking the gov issuing you an ipv6 address that you must use to connect to the internet. But it's also you're id too, since nearly all services are either online or getting pushed that way.