Re: Mapping plan
"The way to encourage ipv6 adoption is to make it a desirable feature that users demand from their ISPs"
What you're recommending here is a bit like extortion. The plain fact is that for 99% of end end users, IPv4 vs IPv6 doesn't matter. This is an issue that matters to ISPs and other industrial routers.
I disagree with the notion that it is OK to artificially degrade the end user experience just so that users will get mad at their ISPs.