Maybe in the future iteration of this chapter, you can talk more about the challenges and constraints from the perspective of the whole eco-system of VR/AR related technologies. For example, how to create a seamless transition for users from mobile phone VR goggles to the standalone VR system, or how to engage users interacting more with the standalone VR system.
Another point that I would like to mention is that I think holography and volumetric display are other types of 3D visual output which might be the future trend as well. So maybe in a later version, you can mention those kinds of 3D visual output in addition to the mainstream technologies such as AR/VR?