ARM has been in Chromebooks for a while. 90% of the desktop has been Microsoft Windows for about 2 decades so it's really up to Microsoft to try again.
Ideally, Android and iOS will evolve so phones and tablets replace the desktop for more people.
Ideally, Android and iOS will evolve so phones and tablets replace the desktop for more people.
What makes a laptop a laptop is a decent keyboard and a reasonably large screen. There is a fundamental mismatch between the screen size comfortable for the eyes, keyboard size comfortable for typing, and device size comfortable for holding in hand. Because of this, I don't think phones and laptops will ever converge; tablets and laptops are already actively converging, though.