Someone else with a more thorough understanding of the IPv6 address allocation procedure can explain why there will never be a ham-radio-only block of IPv6 addresses akin to the IPv4 AMPRNet 44/8.
It would not be a good idea to have that, because we would again be faced with the difficulty to get it connected and routed. The whole tunneling and BGP issue all over again.
When we just want some IP space on internet it is much easier to have everyone use the IPv6 netblock they get from their local ISP, and compile some list of netblocks that are assigned to hamradio that way. So everyone just connects their stuff to internet, and where required imports some list of netblocks that they want to talk to.
The distribution of that list can be done using similar mechanisms as are now being used for the tunnel mesh: - use a file that is posted somewhere and that can be downloaded - use some API to retrieve the data (like on the portal) - use a central system that sends the info using some routing protocol (like the RIP daemon) - setup an ad-hoc mesh network that distributes the info peer-to-peer
I think the latter option is the best. We can use multihop BGP where everyone connects to a couple of friends and maybe some higher-tier service in the country or continent and they advertise their local netblock(s) there. BGP will compile a table of all netblocks advertised by hams, without any need of a central service or authority. You only need to setup a couple of peerings (a full mesh is not required) so most outages will be covered. This table of netblocks will not be used for routing, only for source-address filtering for ham-only communication.
The actual routing over-the-globe will be done directly by the ISPs, no tunneling or special arrangements required, the netblocks are just part of their standard allocation.
Locally, you can route over radio in additional to this, using whatever routing protocol is locally customary. When properly configured, radio paths will be taken where possible and other traffic will be routed over internet.
I am not the only one proposing this. Daniel Estévez EA4GPZ and others have written about it as well. The reason this is possible on IPv6 is that you normally get a large chunk of addressing space from your ISP so you can easily carve out netblocks to be used for different purposes. When getting IPv6 from your ISP, you should check that they DO assign you multiple netblocks, as is recommended in all IPv6 deployment strategies, but not all ISPs do understand that. (also, it is of course best when your allocation is static and does not change every day or so)
Rob