As much as I've tried to be realistic about what they'll do with the new models, at least some of me is hopeful enough to come up with some ridiculous fantasies about what they could do but obviously won't. My top three are:
1) Different casting animations that interact with weapons. I'd love to channel a spell through my staff or direct spells with my dagger if I had it equipped. As it is your weapon is practically invisible as a caster, and it sucks. Maybe even class-specific, like warlocks could use daggers to cut open to the nether and that's where your fire comes from or something.
2) Enough creative license to give a lot more character for racial animations. There's a good amount of character and flavour for a lot of the races, but some have so much unused potential. Humans are so boring, but I don't know what could be done about that. Dwarves could use a lot more weight behind their strikes, full-body movements but less actual jumping. Gnomes and Goblins could obviously make do with more jumping. Make Draenei vindicators use heavy overhead smashes as if they are smiting someone. Make Blood Elves haughty and arrogant and graceful, spells blossoming from dismissive gestures. Orcs that are savage and uncontrolled, like the Orc in the original cinematic. Make them savage even when casting, more arm movement and gathering of power to unleash it. Night Elves that are reckless and graceful at once.
3) Animate robes with their own set of bones too. I want flowing sleeves and swishing hems. I want pieces that ripple when I move or cast. Doesn't have to be realistic, just has to have something going on.