I found this a very interesting look at the current tools and techniques available to reduce reliance on IPv4 and NATs. While I don’t foresee IPv4 going away any time soon, and I’m not sure IPv6 is an improvement per se, I do like to tinker with IPv6 in the home LAN.
(Edit: to be clear, I am not the author.)
The problem with steam was reported on github in 2014. The ticket is still open.
I don’t think the Nintendo Switch even has IPv6 in the OS.