Of Course as Kopin is or will find out the display is half the battle, eMagin has a pretty good head start on optics and prisms

redmercuryvendorKickstarter Backer Duct-tape Prototype tier 1 point an hour ago 

The OLED microdisplays themselves are nothing really new, OLED microdisplays have been available and used for HMDs for a long time.
The problem with microdispays is that because they are physically small, as you increase field of view, you decrease the exit pupil, to the point where as you try and 'look around' the display your physic pupil exits the area within which the display is in focus. That is the fundamental optics problem that would need to be worked around before microdisplays can be used in high-FoV HMDs. So far, eMagin are the only ones to have demonstrated a prototype that achieve this, using fused-fibre faceplates to change the effective exit surface (to get a 2D curved exit surface from a rigid planer display

.http://www.schott.com/d/lightingimaging/8daf9710-460c-44e5-9286-0f73fb321673/1.0/hmd_display_us_july_2013.pdf

https://www.reddit.com/r/oculus/comments/5uv90d/tackling_the_highres_display_needs_of_vr_kopins/