To me that sounds way too costly (especially if they need to be an x86 licensee). And managing a heterogenous platform (HW/FW/OS) is damn hard without even cons

To me that sounds way too costly (especially if they need to be an x86 licensee). And managing a heterogenous platform (HW/FW/OS) is damn hard without even considering the user experience standards that Apple are proud of. I think they will take a different approach. Put a decent keyboard on a future iPad Pro. Make iOS more like macOS. And then they'll eventually kill macOS.