Aonuma *did* mention making improvements to the actual gameplay, but his examples were just your typical "Now With Full Functionality of the Wii U GamePad!" fluff. Besides, I have a sneaky feeling that if content that was cut from the game was put back in, it would look an awful lot like certain areas from Twilight Princess.
Certainly the Picto Box improvements could be made.
Big question is: Will they finally trial full voice acting?
This would actually be the perfect time for that, but judging from that fall release date I'll say no.