> I'm sure internal company LAN's will remain IPv4 behind a proxy for decades more
IPv4 will continue to exist in limited capacity as long as network hardware supports it. With increasingly more network hardware suppliers phasing out IPv4 support for cost reasons, we will see it dying quickly.
Internal company LANs will never switch, both for cost reasons and because IPv6's addressing choices are badly suited for it. Maybe one day companies will abolish the internal LAN and move to zero-trust, but until they do IPv4 will stay. That's a big enough market to be supported indefinitely.
IPv4 will continue to exist in limited capacity as long as network hardware supports it. With increasingly more network hardware suppliers phasing out IPv4 support for cost reasons, we will see it dying quickly.