If the AR floating windows/screens work as they advertise, then it replaces 1-2-3 screens, in whatever configuration you want them in. You connect it into a gaming PC and use the augmented floating windows as virtual monitors. Then use a mouse or whatever, it's more about the windows.
Later you want to see a movie. Minimise all your virtual monitors and deploy a big ass monitor to watch it in a big screen, without moving from you comfy gaming setup.
I'll wait until third party apps implement this feature and the price gets at least halved. I'm the only one I've seen that has mentioned this use case but I honestly feel like it has potential.