It looks like only mobile networks are embracing the change to handles the volume of mobile devices. The evolution of WiFi/phone hardware is quite fast, so they're not stopped by anything legacy, no ipv4 only devices and no one needs static ip on mobile.
It does have an interesting effect though. Apple now have a mandate that apps must work in IPv6 only mode, so they need to be developed and tested for it. This in turn means they need an IPv6 network to test it on, giving enterprise a reason to at least enable it (even if they haven't transitioned any internal services).
I believe t-mobile forced that on apple. T-mobile sells enough Apple phones that they can call Apple and say we need this feature in all phones we sell and Apple will do it. It isn't clear who would lose more if t-mobile decided not to sell the iphone but it isn't one Apple would want to risk.
I have no doubt Apple already have people wanting to do this which is another reason Apple wouldn't push back. They already had people wanting to do this, and so getting a few business people who otherwise didn't care on-board is enough to push the decision.
