Roland Moore-Colyer on tomsguide.com:
Given the cult-like following Apple has, if it can make a 12-inch MacBook that sits somewhere between say $600 and $900, and retains a premium design, then it’ll almost certainly sell like crazy. This is another incentive for macOS app developers to get on board as they’d have a strong guarantee that efforts to rework their apps would pay dividends, both figuratively and literally.
Not sure destroy is the right word. But high-end Chromebooks and mid-range Windows laptops would suffer, and I would love the clarity of recommending a MacBook on the $800 range.
However, the question would be how Apple would differentiate with iPad. Historically Apple has no problem cannibalizing themselves, but always to push a newer technology. To do it as way to offer options will be a new approach. One that I don’t think will happen under Tim Cook.