I really, really hope the five triforce pieces are in new mini islands/ mini dungeons. I swear in that last Nintendo Direct trailer, there was a new island with a moblin in an arena area. Can't wait!
They're not going to be anywhere new. They're going to be in the old Triforce Chart chests that are gone (at least 5 of them will be). Meaning NOW you can find them while still doing the main quest after the first dungeon. IMO, pretty good change in general.