IPv6 would get mass adoption if people destroyed the internet and started over. They should have done that in 2000. Missed opportunity. Let's not miss this one to get the real Bitcoin.
https://tools.ietf.org/html/rfc1340,you can find a lot of RFCs in this site, it depends on the definition of "major upgrade", I think BCH is doing what it should to do, for scaling.
I don't see one major update there at all. Just a link salad. I give you a much simpler counter example. The Netscape browser on my ancient 2002 laptop still shows many websites.
If you think https://tools.ietf.org/html/rfc791 defines IPV4, and that's the base of the internet not including any of the extension/ high level protocols, I am not arguing with you.
POS is not ready, POW is still the best way to achieve decentralized consensus. BCH will never refuse technologies which can make it better. Scaling is the most important thing.
If you take a look on every success technology achievement, no technology lock themself. IP protocol upgrade rarely because it relate to hardware. Incompatible change cause greate lose
bitcoin runs totally based on software, except the asic miner. upgrade is an easy thing, just change or add a few lines of code will not cause someone lose money.