There are a lot of changes needed, especially in (old) corporate environments.

I do use ipv6 at home, and at some of our customers, but some of them would have to essentially redesign their entire networking/vpn/security plan (and yes, existing ones are not good, split horizon DNS is almost always present, DHCP is not only used for security, but also for provisioning, there are products that scan subnets and provide reports on devices required for various compliances ...). And that is a hard sell, for what they see as next to no benefits.