1. Once the world collectively moves on from v4, you stop assigning v4-mapped v6 addresses. And nothing stops you from assigning two v6 addresses to a single iface in the meantime.

3. Yeah, it shows my ipv4 only, and I have both. Do you not have a v4?

6. No, there's not, but the reality is everyone you're trying to switch over to v6 is already used to v4, and it's like herding cats.