Well, Windows OEMs tried putting Windows as is on tablet laptops—and from what I understand, nobody liked it. I’m sure some people accepted it, and some would also accept it with macOS, but 1) very doubtful that this is a significant market, and 2) that kind of shoehorning is just a very un-Apple thing to do. They always go for the “magical” experience.
The form factor conversion of using a keyboard and trackpad is a little more realistic, since the Magic Keyboard already exists, but that still doesn’t make macOS on iPad likely for reasons I stated earlier in this thread, but mainly, the dual OS experience comes with compromises that I think are subtle in concept, but will become obvious in practice. Those compromises will likely make it a niche use case, and not “magical”, which makes it uninteresting to Apple.
I do think Apple believes carrying two “magical” devices is more “magical” than carrying one un-“magical” device, for those who need to. But also I think most people don’t need to carry both. They can leave either the MacBook or iPad at home (but always bring the iPhone, which covers a lot of functions that a MacBook cannot, and they work pretty easily together with Continuity features), probably usually leaving the iPad. But if one does often need both laptop and tablet functionality together, an iPad mini often makes for a better companion to a MacBook. Its small size makes it very compelling and even optimized for traditional tablet-y things, while the MacBook handles everything else.
