APNIC reminds us that "there are now a large number of ISPs, data centres, cloud services, and software that now support IPv6" and "enabling IPv6 can be as simple as clicking a button on your WiFi router."
I turned it on, with Comcast I received an IPv6 route but no DNS server. Fortunately, Google Public DNS has unmemorable addresses, which I was able to configure manually.
It works. "There's only one thing left for you to do: Turn it on!"
[ ed: What are the alternatives to Google's Public DNS? ]
A Swiss VM hosting provider has a technical blog post about how to kill IPv4 completely on FreeBSD. That is to say, turning it completely off, not just preferring IPv6. They then solicit concrete solutions describing, along with a proof of concept, how to turn IPv4 completely off in other operating systems and allowing them to communicate with IPv6 only.
Earlier on SN:
Vint Cerf's Dream Do-Over: 2 Ways He'd Make the Internet Different (2016)
You have IPv6. Turn it on. (2016)
We've Killed IPv4! (2014)