[classified]

IIRC, the Python used in the macOS vim(1) is still 2.x. So at least on a Mac it won't be possible to just move on to Py3 and forget / uninstall Py2 for the foreseeable future.

[cinnamonheart]

I think you can just do

    brew install vim -- --with-override-system-vi --with-python3

To get a vim with python 3 on mac os. You are correct that it defaults to python 2, though.

[throwaway333444]

Additionally, the next version of macOS, out this fall, will remove/hide the system version of python (python2) from users.

Look under Scripting Language Runtimes

https://developer.apple.com/documentation/macos_release_note...