Private backplane networks would presumably be using static ULAs. What's so hard about "ping fc00:abcd::2"? > what about the vast majority of people who have l

Private backplane networks would presumably be using static ULAs. What's so hard about "ping fc00:abcd::2"? > what about the vast majority of people who have less expertise and less time/resources to deploy complex configurations? "Simple things should be simple and complex things should be possible." There exist IPv6 ISPs that give you a modem/router that you plug your stuff into and there is nothing else to configure. They could all do that. That covers the large majority of people who just want to internet as quickly as possible. If you want to have complex internal subnets and backplane networks and things like that, this is a thing that requires technical knowledge to begin with. I suspect the reason people continue to use IPv4 for such things is simply that they're more familiar with it and it still works. And so what's wrong with that? The primary advantage of IPv6 is that it gives every device a globally routed address. It still does that if people carry on using dual stack with IPv4 until the end of time. Or however many decades until IPv6 has enough penetration that people have gotten used to it and start to turn IPv4 off. You can use IPv6 long before IPv4 ceases to exist.