If there is something I would like to see it would be a flying map above the ground of tyria. Something with floating islands, rocks, airships and a lot of verticality. A map without any kind of ground. Maybe just have clouds and a distant image of the tyrian landscape below and if you fall and miss maybe a timer to port back to a waypoint of this new map you are ported into one of the ground maps of Tyria at random.
I think with skyscale, griffon and gliding we already have good tools at hand, but it definitely would need new mechanics to gain height and probably some ways for air battles too.
I always think about skyward sword here for reference.