That's strange and would be a pretty big about-face. Apple, the most locked-down and proprietary OS vendor, has great support for third party password managers

That's strange and would be a pretty big about-face. Apple, the most locked-down and proprietary OS vendor, has great support for third party password managers in their OSes and has been improving that support in recent years. If they kick 1Password etc. out of the Mac/iOS ecosystem that would be a pretty big deal. It could happen, but why would they do so?