[lxgr]

Why would we keep around a whole separate Internet? Dual stack was always only intended for the transition period.

[g8oz]

It's very hard to get rid of old standards.

"The past is never dead. It's not even past"

[lxgr]

Of course there's an incredibly long tail here, but in the big picture, "nobody except some people maintaining a few legacy systems ever need to learn to work with this protocol anymore" is practically the same thing.