If they are going to add other types of mounts they need to be careful. It has to make sense and match the FF world, or it will just seem tacky.

I think asking for flying mounts is asking to much. The world is split into zones so you couldn't just fly anywhere, the game world isn't built to be viewed from the air. Blizzard had to rebuild zones to enable flying on WoW. I can't see Square doing that nor do i want them to.