A headset having 4Kx4K panels for each eye doesn't make it a substitute for a 4K monitor, the distortion through the optics means a virtual display will appear much lower resolution than that. The rule of thumb for headsets with 2Kx2K panels is that a virtual theatre covering most of your field of view has a perceived resolution of about 720p, so you can maybe expect about 1440p from the Apple headset in the best case where the virtual display dominates your field of view, and less than that if the display is smaller.
1440p is good enough for 27in monitor. If I can have an array of those where it can track my focus between then and it was seamlessly integrated to OS I could see the value.
