I see "value" in a lot of things that are ultimately just nerdy entertainment.
I saw value in OpenDoc, too. What I never quite saw was an answer to: OK, can you make an actual app, with OpenDoc components, that is awesome to use and that people will prefer over existing ones? (Turns out: no.)
And similarly, I used Windows 8 extensively from its early previews all the way throughout the point of Windows 8.1, where they had started undoing some of the damage. It was bad, because "no compromises!" was really "a
lot of compromises".
In 1994, we had a Power Macintosh 6100. When you hit cmd-return, it would boot from Mac OS into Windows 3.11. How did it do that? It had a whole additional daughterboard with an x86 on it.
It was very interesting from an engineering point of view, and mildly useful when you really
had to do that, but also an utterly terrible, un-Apple-like user experience. And that was even
better than what you proposed, since both machines could run simultaneously (although you could only see and interact with one at a time); you did not have to shut down.
If Apple really does, as you propose, bring up "you can now run macOS on an iPad! All you gotta do is dual-boot, and oh, touch does not work" as a grand new feature at a WWDC, I'll really worry that they've jumped the shark and/or gone back to their poor 1990s' decision-making, with all its "just because you can really doesn't mean you should" warts.
A company that does that thinks that this is a good tablet:
Rather than wait several more years until they can
make a good tablet, which became the iPad.