While ago there was a post from Epic Staff:
No info about this I believe since then… Google Cardboard has wider audience, since its much cheaper to get cardboard then Oculus Rift for example (or for some even GearVR), so its an interesting area. I don’t know if it is possible to in some way use GearVR build for cardboard? I just hope they haven’t dropped it out since they started working with Samsung for GearVR.