Earlier quoted context omitted.
If they bumped the storage options, I see no reason why the phone couldn't run iOS and the plugged-in desktop-phone run macOS. Photos, email accounts, chat logs, etc could easily point to the same data on disk so you have two operating systems working off the same user data. A lot of the UI infrastructure for this is already there in the form of iCloud shared photo libraries and iCloud drive, which lets you access fi…
To build on what you say, once one plugs in their iPhone and MacOS boots and is on display, the iPhone touch screen itself could then be used for the trackpad. I could see a keyboard/dock combo where one could drop in their iPhone.
I don't see Apple blurring the lines of mobile/desktop UX simply because the ARM chip now enables the opportunity but I do see them moving their macbook line to ARM for cost reduction and increased leverage over Intel.