https://youtu.be/zxM4vN_4jJY
With peoples already hacking VR headsets like the DK2 to have AR, and Vive including the room visual cues, its only a matter of a few iterations before its integrated in all VR headsets. Eventually with Leapmotion (hand detection technology integrated in the headset itself.
AR and VR are bound to merge and become just one product.
It will go to something quite "clunky" like this
With a couple of iterations being just better optics and adding the camera for AR.
To some kind of mix between hololens/google glass/VR
To transparant glasses that can go opaque for full VR immersion or simply show AR stuffs in your daily life.
To eventually some crazy sophisitcated contact lens (or a bionic eyes for the peoples who will go willfully into augmentations).