What we need is a single MacOS that can run an iOS-like touchscreen launcher and dumbed-down 'apps' while operating via touchscreen, but with a keyboard+mouse connected switches back to 'productivity mode', exposing the full power of MacOS.

MacOS can basically do this already, running iOS software on Macs. It's just a matter of choosing to unlock the potential of modern iPad hardware, putting the same OS on iPads and Macbooks. Full software compatibility. iPads that can be more than locked-down toys.

But would Apple ever give up the control and App Store revenue that locked-down devices provide?