Me too, I only signed up to express that it would be a great feature and to share some info: on AVS forum Nilzilla found a device that could be doing exactly the trick what we were looking for: the synchronization and side by side packing of the 2 pictures from different sources:
http://www.avsforum.com/forum/showthread.php?t=1850074
The device he proposed has resolution limitations, but we could get together and link up a 4K multiviewer with a dual play screen and give it a shot!
Could someone from LG please test it and verify if it worked? If nothing else but this could bring back the reason for passive 3D on a 4K.. I would be willing (any time) to pay 10-15% premium on a 3K+ OLED 65 inch 4 K TV. LG please take heed and action!