The television sets using 21:9 aspect resolution do have a higher and non-standard native resolution of 2560×1080 which may be Ok for 2D content pushed over HDMI 1.4 interface is not OK for 3D content. The reason behind that fact is that HDMI 1.4 specifications for stereo 3D content support up to 1920×1080 resolution with 24Hz in 3D mode, so there is no way to push even higher resolution in stereo 3D mode over that interface. This means that you are pushing 1080p 3D video to the TV set and then it gets processed in some way in order to be displayed to cover the whole wide display, kind of upscaling and cropping of the video.  This again should be quite OK for movies as with 3D movies in 16:9 aspect ratio you still get the black lines at the top and bottom, but what about playing games or photos in stereo 3D mode where you still need to push 720p or 1080p?  Considering the fact that 24Hz 3D mode is not very responsive for most gamers, you would have to resort to playing games in 720p mode and upscaling that do the native resolution of 2560×1080 might lead to not so good visual quality, especially of the game does not have Anti-Aliasing support. But what will the 21:9 aspect ratio TV set do when you are sending 1080p or 720p 3D content which is 16:9 aspect ratio? The television set will upscale the image just like it does with a movie, but since you are not going to have black lines in the game window you are actually going to loose some of the image at the top and bottom and in games these parts usually are used for the HUD display.