There's no way Apple would make a VR headset tethered to another device. To be on-brand it has to be elegant, which means all-in-one. It probably needs a new OS... certainly none of the UI from iOS can be reused, and it needs VR-specific heat and power optimizations, probably with a new low level graphics toolkit.

From Tim Cook's statement it seems pretty clear that they're going to wait until they can do AR glasses, which also fits their anti-nerd brand strategy. AR is more social, more human.

Although when the standalone Google/Oculus headsets hit next year I suspect people will be surprised how well they sell. The mobile VR app ecosystem should hit puberty around then. Assuming Oculus/Google can hit a $600 price point I think we'll see an iPod-like growth curve in that category, which would lure Apple into the market for sure.

Isn't AR less immersive, less good as means of escapism ? And less "Addictive" ?

and that means VR will have a larger market ?

Immersion is nice for "experiences", but AR has the potential to be used all day, just like smartphones. Besides, they'll eventually converge.

The problem is that while potentially more immersive, VR is more exclusionary. By definition it's not an experience that shares well with meatspace. So it's easy to cut off and be cut off from other people in the same room. That's fine for a teenager in their room but not so much someone living with a significant other or children.