Taking up one of my old ideas here, though it would require a larger, touch-capable e-Ink display:

How about combining this project with dirkvl's project and making an e-Ink keyboard? By adding the slider mechanism from the qwerty-OH, and adding a thin silicone overlay that gives a tactile segmentation of the display into key-sized squares, it might be possible to have an e-Ink-keyboard that becomes thinner than the qwerty-OH and can adapt on the fly to any keyboard layout you want.