The only issue I see is that they'll have to change how brew bootstrap itself, but it should be trivial for them to just make the installer download a minimal r

The only issue I see is that they'll have to change how brew bootstrap itself, but it should be trivial for them to just make the installer download a minimal ruby runtime. One good upside from this deprecation is that lots of scripts naively containing "#!/bin/python" and such without invoking them through /usr/bin/env will stop working on macOS, which is good.