Nice graphic, but the arguments don’t really support the conclusion.
Let’s address the final statement first:
“Designers: say goodbye to the rectangle.”
What you don’t show is as important as what you do show, so the designed rectangular frame will always be important for concise curated information in central vision. That said, designers need to learn how to communicate effectively in a 3D immersive canvas.
The arguments for a diminishing market of screen sizes, while hyperbolic, have some value. Virtual screens in VR/AR environments will replace some physical screens, but there will always be a need for shared screen experiences without headsets. Consider the grandparent demographic or the parts of society that won’t be able to afford the headset, computer, app, and network required to view shared content in VR/AR space.
There’s also the issue of vergence-accommodation conflict which causes fatigue and discomfort for many people, preventing them from using the headsets for an extended period of time. Traditional physical screens don’t have this issue because the focal distance and vergence distance are equal.
Like all new technology, AR/VR isn’t going to completely replace existing technology. It’s a new category that will co-exist with current options, allowing us to pick the best tool for the job.