a phone, an ipod with touch controls and an internet communications device.
Of course, the iPhone is now marketed as a multipurpose computing device, a 4k video camera and an AR viewer, so things have moved on.
It would make sense to me to add more power-user features to MacOS in future, rather than making it more iOS-like? Apple made that mistake with Lion and the app grid with folders and massive icons that can't be resized is crappy to this day.
iOS won't be a MacOS replacement at least until all Apple's professional apps are available on it. Processing-wise they are probably only a couple of generations away from being able to support Final Cut Pro, Logic X and XCode, but interface-wise there is a huge amount of work involved in reinventing those apps as touch-first.
I think they’ll just make iOS more and more attractive, while they make macOS more... iOS-like? And in turn, watchOS is an added benefit to iOS that macOS won’t fully utilize.
There’s some sort of uneasy tension here, I’ll be interested to see how it (slowly) develops.