Re: "the world is clinging stubbornly to IPv4"
> Their solution was to just drop IPv4 altogether and only have a bunch of edge servers speak dual-stack.
The large finance company I work for is going down the same road. We had some struggles during the last corporate merger due to significant overlap in RFC 1918 network ranges. We also have to use source and destination masquerading on our private tunnels running to third parties due to similar range overlap.
Our long term goal is to have our perimeter firewalls and load-balancers running dual-stack so they can perform NAT-4to6, while having everything else behind them running native IPv6.
Besides eliminating future potential merger issues, the company is motivated to complete this migration so that they can sell their sizable holding of IPv4 addresses while they still have significant value.