Wow, I have to admit: You have some great ideas and even better mockups in this article.
I’m one of these Apple users that tried to go the iPad-only way a few years back when I first bought the iPad Air 2. It worked fine most of the time, but as soon as I had to edit a video (iMovie for iOS is just not good enough, I need Final cut or Adobe Premiere) I was forced to go back to my Mac again.
Same thing happened when I had to write papers for University. It’s okay to write a Medium article on my iPad (even without an external keyboard), but when you have to do research and advanced formatting, it gets annoying soon.
Nowadays I use the iPad most of the time, but there’s always at least three or four occasions a week where I have to move back to my Mac because the iPad is just not good enough.
I guess it’ll take Apple a few more years to adopt a universal system like you just presented and I really hope it comes rather sooner than later! It’s just, well… the future of mobile and desktop.