Unless they really want a special “room” to watch from I don’t see the point, I imagine Apple will make 2D video play in a variety of virtual environments.
You know how Amazon has that great feature where if you pause the show you get to see links to the actors currently on screen? A vision pro app could give you that same information off to the side so you don't have to pause. Eye tracking takes this a step further. I'm looking at a specific actress and signal that I want more information about her. I can get just the information about her, not the other actors in the scene, and I can get it in a pane that doesn't block the show. No pause needed.
In the 2010s, a lot of shows had companion podcasts that you had to start at the same time as the show. Or they would have companion apps. I can think of easy ways to improve this with a vision pro app.
A lot of other changes I can think of require collaboration with content creators. Things like signaling that there's a bit of commentary about this specific scene, or embedding easter eggs that you have to look at to uncover, or creating jumping-off points from a show that lead to additional content like Trent Reznor's Year Zero.