This feels a lot like the arguing that went on during the transition to Python 3. The Python 2.7 hangers-on were so preoccupied with themselves that they didn't notice that the pool of people interested in having the argument at all was getting smaller and smaller.
Until somebody turned off the lights, that is. It is not much fun arguing with yourself in the dark.
I think that's what needed and needs to be done here. I will agree with the IPv4 advocates on one thing: IPv6 adoption has been slow in part because it doesn't work like IPv4 + kludges. That is the point. Clinging to IPv4 standard practices while you switch is just going to make you miserable.
In 2006, the hesitation to go to IPv6 made sense. Support was spotty. In 2026 it does not. IPv6 support is now more than adequate, and a clean cut will force the stragglers to get their asses in gear in a hurry ("fix your IPv6 support RFN or enjoy nobody using your product"). Change is painful, learning new stuff when you were getting by just fine on the old stuff is painful, I get it. But it will happen whether you like it or not. Why not just get it over with?
I finally made the switch to IPv6 last year, and I wouldn't go back.
The pain of change is real, but mercifully, it doesn't last. Within a year this debate will seem quaint.
As with IPv4/IPv6, with Python 2.7/3 you had, even at the very end, a group of stubborn maintainers who didn't put in the effort to transition.
The hard end of Python 2.7 support took care of all that in a hurry.