> spatial hand tracking as a new UX paradigm

I only see this as a supplemental feature for certain use cases (coarse-grained 3D operations). In general nothing beats the efficiency of working with a keyboard for navigating application functions, or (at least with current technology) the mouse for precision 2D navigation/selection. Their advantage being precise and definite/discrete input.

For actual work, even with a VR headset I see myself still mostly using keyboard and mouse.