This is very good example how an ISP can move to IPv6, but my comment was mostly speculating about the IPv4 part. Even US T-Mobile needs to have a bunch of IPv4

This is very good example how an ISP can move to IPv6, but my comment was mostly speculating about the IPv4 part. Even US T-Mobile needs to have a bunch of IPv4 addresses to maintain it's IPv4 proxy (and the size of IPv4 address space they need is determined by the size of their expected customer base). So I was wondering when/if company in a similar situation would not feel the need to maintain IPv4 proxy or would seriously evaluate whether they still need it wrt of cost of the IPv4 address space necessary and potential loss caused by customers who would not be ok with missing IPv4 internet. But maybe such speculation is missing the point, and cost of the IPv4 addresses is not as bad as keeping dual IPv4/IPv6 stack running in a datacenter. I don't know. That said, you definitely have a point that right now, I should rather wonder how many other ISPs are moving to IPv6 only stack with IPv4 proxy like US T-Mobile did. Here I would definitely expect that telcos today are moving in this direction when planning new infrastructure (eg. for edge).