I expect homebrew to switch to installing their own local ruby via a zsh.

They already install their own local ruby today, but use the system-ruby as an entrypoint.

Good point. Hopefully the Homebrew installer script will bootstrap this for you. They already build and distribute binary packages, they probably can easily download the existing Ruby package and execute it.

Except it’ll be the latest, and then easily updatable after that.

Expect package installers that make the whole thing easier and more secure (signed packages vs a curl | /bin/sh)

You install Brew every day?