What I'd like to see is something similar to Windows 10's "tablet mode"
An action within the UI to switch to a more iOS feel for use as an iPad style device, and vice-versa to a more Mac style device.
I imagine both macOs and iOs would have to drift more towards each other but that could be a suitable hyprid, and the prospect of actually having a fully functional Mac in my pocket that can be my phone on the go, and be plugged into a monitor later as my workstation is appealing.
I had an idea to do something similar once for a Uni dissertation, involving a rift mounted with two cameras to do a very hacky and cheap prototype version of what you've described.
My supervisor shot it down because "Google glass will do that" :(
That function is thenable so following it .then is called and the result or error is passed to the first or second function respectively.