Homebrew is a great system for most situations. Great effort by an amazing group of volunteers. To fix the very real issue you describe, I would like to see a

Homebrew is a great system for most situations. Great effort by an amazing group of volunteers. To fix the very real issue you describe, I would like to see a --isolate option for mission critical packages. All the dependencies would be contained in a separate, package specific directory within /opt or /local. The rest of the dependency management could happen without affecting the isolated package.