Imagine an executive placing their phone on a magnetic dock as they sit down, which automagically connects to the screen and gives them access to everything they were doing before. Also easy to imagine a university computer lab where everyone brings their own compute and IT doesn't have to manage physical desktops.

I'm skeptical that there's "no demand" for that kind of functionality rather than a lack of good implementations. Look at how popular wireless CarPlay and Android Auto are. They're essentially the same functionality, but tailored to an in-car experience instead of desktop.

Imagine executive tapping their phone down on reader, and it pops up everything they were doing, and they get to keep using their phone.

The first flaw in the idea is that computing is cheap. You can make a computer the size of a phone for people to carry around, that has been tried but failed. The second flaw is that everything is in the cloud, only developers and offline need local access to their files. The cloud also means that can desktop in the cloud.