Several things seem obvious to me - I may be wrong but we'll see:
-The tablet will have a new UI.
-Elements of that new UI will filter down to the next gen iPhone.
-Apple Patents have have depicted some kind of 3d-ness to the new "mobile" UI
-Given 3d-ness, it would be intuitive to be able to manipulate things in the foreground or background by touching either the front touchscreen or the back touch-sensitive case.
I like this thinking....