> No, the migration is only done when you're exclusively running IPv6.
I don't think that's an informed, thought-out take. The internet works just fine for all intents and purposes if you have some services reachable through IPv4. There is no obligation to shut down IPv4 in order to work with IPv6.
If you're able to go through your daily work seamlessly hitting services with IPv6, that's a successful migration. It matters nothing if an unrelated service hasn't went through their migration yet.