> The 50% stat is really mostly mobile phones on cellular networks, which remain the _only_ major success story for IPv6.

The largest ISPs in the US are Comcast, AT&T, Charter, Verizon, T-Mobile, Starlink, and Google Fiber. They all support IPv6. The only top-10 US provide that didn't support it is Frontier Communications, who is rolling it out.

In other words, the biggest companies who actually do this for a living all demonstrate that you're wrong.

As to your questions, read up on IPv6 ULA which solves all of them. None of the hosts on my LAN depend on having an outbound connection.