UX concept: Making mobile phones' more ergonomic (or mobile keyboards)

About a year and half ago I responded to a question on ux.stackexchange.com titled "How to improve the smartphone keyboard layout?" with a non-standard answer...

Don't be satisfied with a better application, instead make the keyboard more ergonomic by placing physical buttons behind the phone, thus enabling you to type with four finger while holding the phone in the same hand or to type with eight fingers while holding the phone in two hands. This prevents stress to your thumb while using it to type or gesture while holding the phone in the same hand or stress to your index finger while using it to type or gesture while holding the phone in the other hand. In addition, change the roll of the buttons dynamically depending on the orientation of the phone (portrait or landscape) and on the hand holding the phone (detectable using an optical sensor), so that the QWERTY-like layout changes according to how the phone is held, enabling each finger to access more or less the same buttons as on a regular keyboard, no matter how the phone is held.

I have recently heard of the new transparent phones. With these new phones, instead of only visualizing a keyboard on the screen and pressing on the equivalent buttons behind the phone, you could display semi-transparent keys above the application and see your fingers below these keys,

thus perhaps making the concept easier to learn for beginners, yet still enabling the alternative mode of displaying a miniature keyboard at the bottom of the screen to users that have already got a hand of the (qwerty-like) key placement behind the phone.

Update:

It seems like someone has actual made one of these:
http://edition.cnn.com/2014/01/06/tech/web/ces-unveiled/index.html