We're not really expecting to see Leviathan till at least 2.0 - the beasty didn't show up on the map where Mr Moogle and Garuda did.

Version 2.0 will be seeing a graphical system overhaul. The main quoted reason we're being offered a complimentary gender & race change is because avatars will inevitably look somewhat different under the new engine and they want people to have the opportunity to create their character's appearance in a way they like under the new system.

Like that or not, it suggests the graphical system will affect a whole range of things. I suspect the devs are using this change as an opportunity to create a new in-game model of Leviathan to sit inside the new graphical system rather than just pointlessly expand the CG version they currently have in cutscenes as well. If so, that's our draft right there.