[bauruine]

IPv6 is backwards compatible to IPv4 but not the other way around. If you have a solution how to address a 128bit IPv6 address with the 32bits available on v4 I'm sure many people are eager to talk to you. It's just not possible.

[hot_gril]

With a 6-to-4 gateway then yeah. But at that point you're using v4.

[Dagger2]

How do you expect compatibility with v4 protocols/software/hardware/routers/ISPs to work without using v4?

That's a serious question. Do you have a way for this to work? Because I don't think it's possible (for fundamental reasons: https://en.wikipedia.org/wiki/Pigeonhole_principle), and it would be extremely unfair to criticize the designers of v6 for not fixing an unfixable problem.