The translation mechanism would be nat46, which is already experimentally available on things like OpenWRT, so well within domestic-router costing.
Similar to the 6to4 that'd be running on an ipv6-only ISP so you can still reach v4 hosts (of which there will be plenty, for a long long time to come)
(don't get me wrong, my amiga, and oddly my lightbulbs, are the only things in my house not already using v6. I'd love to see it adopted in everything so I can quit thinking about it. But historically, predicting the apocalypse gets rather awkward when it comes and passes. Scaremongering isn't always the best way.)
