Manderville Oil: Allows you to Sonic run/swim, hulk super jump / variation of mount that allows flying (there are a few items in the cutscenes that could be used, or imagination w.e lol).
King Behemoth, Snurble: A big snurble :3
Flammie: Or a Flammie like creature, has a resemblance to Hraesvelgr
I'd like to see some more within mounts, like the manacutter where you're within it rather than on top of it - basically some less prominent "you" mounts and making the mount the center focus (more so than the manaclipper even). Although I understand why most are not that way.
If they never add a shapeshifting job to the game a shapeshifting mount would be cool (if they do, then to that job imo would be more interesting). It could just be an animal/creature/void w.e thing that is capable of all three needed forms of movement, but they may also have it where at different points of travel you shape shift (jump into the air, bird, hit the water change into aquatic animal, ground, something else). Related but, riderless chocobo (either via transformation or just a unique invisible/glamour effect - maybe earned in a covert mission).
Some mount features: Keep it interrupt-able but if possible I'd like to be able to cast on the move, I mean like I start the mount call and can keep running at the same time - doesn't interrupt movement (has a casting bar but does not casue any pause, and yes I am aware you can currently move at the last portion of the casting bar.. not what I meant lol). Can lengthen the time or keep it as in PvP (should be fine either way, since you would still be interrupted and slowed greatly). Would like to see being able to dismount in the air, and the game being less feisty on trying to save your life lol.
Oh hey Slepinir will be able to fly finally, that's cool. Wonder if they'll use wings or go the Fenrir route, also.. more legs? XD