Since Gatekeeper was originally announced I've seen people claiming that Apple were going to lock down macOS so Homebrew wouldn't work any more. I've never seen evidence that this will actually happen (and the people I speak to at Apple point to the opposite).
Yes they do. But the question is, why would they make a decision that will instantly make the machine completely unusable for a substantial portion of their clientele? Also, the portion that arguably gives MacBooks and, especially, iOS devices their value.