… the phone incorporates a double display. When in active use the AMOLED screen powers up in all glory and in standby mode the E-ink display gets active. This essentially means that the E-ink uses very little energy and the degree of transparency of the display shows how much battery is remaining. The more transparent the display, the less battery remaining.
The Second Life Mobile Phone Concept is a neat but with current technology is probably not possible. The transparent OLED display is already here and was demonstrated by Samsung. But an E Ink display, the way it currently works, cannot be transparent.
Another difficult, if not impossible, challenge for this type of design would be the battery: where could it be housed? If you look at the most advanced mobile devices the largest component is usually the battery. Unless there is a revolutionary advancement in battery technology, much space will be required for batteries powerful enough for a mobile device like a smartphone.
There are transparent glass with embedded solar cells, which can generate some power; the amount of electricity will most likely not be enough to support a smartphone but maybe something extremely simple like John’s Phone. The bottom portion to the left and right of the button doesn’t seem to be used for anything. Maybe a small battery and other electronics can be housed there.
Photo sensors can also be integrated into the display itself so a separate camera module that uses the typical lens + image sensor might not be necessary in the near future. A transparent phone is certainly possible but will most likely need to be a very simple phone that uses very little power.