If sometime in the future we are all walking around in the physical world, and we are sporting eyewear that lets us see whatever we want, then we are going to be shown things that are consistent with the immediate physical world around us. Walls, chairs, tables, and other potential physical hazards are going to be made visible.
But beyond that, anything is possible. In particular, we might find that the question of whether an other person is “present” becomes interestingly complicated. For example, we may see another person standing in the room with us, but that person might actually be physically located in another part of the world.
Or perhaps that’s not a real person at all, but an NPC (non-player character), a behavioral simulation created through an Artificial Intelligence algorithm.
Another possibility: Maybe there really is a person standing in front of you, but you can’t see them — in this alternate view of reality they are invisible. This option would be useful, for example, for immersive theatre. When you open a window, you can feel the wind blowing in your face. You just don’t see the person standing in front of you holding a fan.
Yet another possibility: You see a person, but you are actually physically interacting with a robot. When you shake that person’s hand, you are actually shaking a puppet hand. The robot can either be teleoperated by an actual human being, or can be actuated algorithmically by computer.
The more you think about this, the more possibilities present themselves. I don’t know how things will end up playing out, but I’m already convinced that future reality is going to be a very interesting place.