I'm definitely with you on customization being a no-show, especially given that in the contest scenes they show a Sugimori art (it could be Ohmura though) of Brendan/May wearing the same outfit as Pikachu Rock Star/Pikachu Pop Star.
As far as I know, in X/Y your character was always represented by a 3D model because if it was Sugimori art, they'd have to make so much artwork for each outfit combination it would get to the point it takes up too much memory.
Plus, I wouldn't mind if customization didn't return since this is a remake of an older game and I do love May's new "cute" look anyway.