The difference with IPv6 adoption is that the internet relies heavily on network effects: so long as some hosts only have an IPv4 address, you need an IPv4 address for full connectivity, but then if everyone has an IPv4 address anyway, there is no immediate need to migrate to IPv6.
(Yes us Hacker News users have plenty of use cases for IPv6, like self-hosting and peer-to-peer networking and so on; we are not the average user.)
This effect doesn't exist for the Git migration. Each repo can be updated independently; it doesn't affect users of other repositories, and most likely, the majority of devs will work on some SHA-1 repos and some SHA-256 repos with no issue.
If anything, I would compare it with the Python 2 to Python 3 migration, which was also painful, but succeeded eventually (despite being much less necessary in the first place).
> Yes us Hacker News users have plenty of use cases for IPv6, like self-hosting
Funnily enough, self hosting is why I can't use IPv6. I want vlan isolation, but only get a /64 from my ISP.
Fortunately the lack of IPv6 also isn't a meaningful loss anyway so whatever
I just started learning IPv6 with AWS since they charge $0.005/hr per IPv4. Maybe it will be more expensive in the future and eventually it will be the new default.
changing repos to the new IDs would break any existing links to content on the pre-migration repos.
You are wrong with your own examples.
Github is THE main platform for git. If github doesn't upgrade (and their code has been shit and hard to fix/update before) then the shift will not happen. Because yes, you can upgrade your repo independently, but if there is nowhere to push, no one will do it.
IPv6 is (also because of github) a great example for this. You can easily have an IPv6 address next to your IPv4 address, but a lot of websites (e.g. github) don't have that. Why would a normal company use IPv6 if even the bastion of nerds doesn't use it?
And to Python 2's "eventual migration" I can unhappily tell you, that my company (recently) bought an actively developed tool, that still uses Python 2.