Not a twist, but I think the flight sections in maps should be much larger or more interactive. Currently, you just float down to the next section and there really isn't a lot of involvement. I'd like to see more maneuverability with players having to take advantage of wind currents, thermals, and perhaps boosts.
I was thrilled with the new twist of the gravity sections. I love the disorienting sense of movement and not knowing which way is up or down. Shy Guy Falls is probably one of my favorite tracks. I don't know what they could possibly do as a new twist though. Like others have mentioned, maybe they'll add planes or boats or something. Nintendo should make it to where you can get out of your vehicle and go through obstacles on foot, a la the mario games.