I'd argue it has, but that's not the point. IPv4 is pretty much mandatory for most users of the internet. Yes, individual users probably neither know nor core whether they're on IPv4 or IPv6, but it's so difficult to run IPv6-only that you just wouldn't bother.
Trying to teach someone about how to use ULA vs. GUA only leads to headaches. In fact, I'd go so far as to say the reason why the internet became so ubiquitous was because of NAT -- static internal addressing is pretty much fundamental to an easy-to-use experience. Having multiple addresses on a host only makes things far more confusing, so people don't bother, because IPv4 justworks.
I'd argue it has, but that's not the point. IPv4 is pretty much mandatory for most users of the internet. Yes, individual users probably neither know nor core whether they're on IPv4 or IPv6, but it's so difficult to run IPv6-only that you just wouldn't bother.
Trying to teach someone about how to use ULA vs. GUA only leads to headaches. In fact, I'd go so far as to say the reason why the internet became so ubiquitous was because of NAT -- static internal addressing is pretty much fundamental to an easy-to-use experience. Having multiple addresses on a host only makes things far more confusing, so people don't bother, because IPv4 just works.