Also, the article is old. It doesn't mention NAT64 which got rid of the big compatibility issue of IPv6 hosts not being able to talk to IPv4 servers. The other

Also, the article is old. It doesn't mention NAT64 which got rid of the big compatibility issue of IPv6 hosts not being able to talk to IPv4 servers. The other way, IPv4 to IPv6, will never happen and could never happen with larger address space. People talk about extending IPv4 address space but never explain how they would solve the compatibility. I thought of scheme where could put the original IPv4 address in option header on every NAT transition to make a variable length address. But that would require changing every router (and lots remove options when NAT), every program, and every protocol. All the stuff that needed to happen with IPv6, with the downside of keeping IPv4 allocations and NAT. It also mentions a lot of problems with IPv6 that have since been fixed. There is a valid complaint that IPv6 changed too many things so it took a long time to get replacements working.