I would have to disagree about other OSes. MacBooks are used for DS at Google. Models are moving to and will most likely all exist in the cloud. I barely know any engineers and scientists who are using anything other than MacBooks. That includes robotics, DS, analytics, blockchain etc.
Anyway, I'm just talking about enough power to run notebooks, dashboards, visualizations, etc. Not so much big data. Besides, GPUs are highly prevalent in Deep Learning and Deep Learning is a small part of ML. That's why I was thinking 32GB/8GB might be enough for private research.
If we're using MBP as a Terminal then we might as well use an iPad Pro. Which is what I'd like to do if I didn't need Xcode as well.
Btw, AMD ROCm looks promising.
Getting started with ROCm platform
towardsdatascience.com
Guest post by Mayank Daga, Director, Deep Learning Software, AMD
medium.com
AMD have added code to TensorFlow. There is support for TensorFlow which is progress towards AMD supporting AI libraries.