First and foremost. Its a rumor, but

Holy Crap. YES!
Kingdom Hearts HD Remix To Be Shown At E3 2012 For PS3, Wii U, and PS VITA - Dual Pixels
It includes KH 1, 2, Chain of Memories, 358/2 Days, and Birth By Sleep.

New side missions
358/2 Days engine will be tweaked to more in line with current titles. Since you can't really play a dual screen on the systems its going to be released on.