"For cinematic CG the models, textures and other assets are absolutely huge - it's not unusual for a single shot to come to hundreds of gigabytes."
I recall reading an article, IIRC in CineFX, about the Godzilla model in Gozilla 2000 (the Devlin and Emmerich film). The textures for their Godzilla model alone were something like 900 MB.
Honestly I wouldn't be surprised if Pixar introduced a renderfarm hosted in Azure.
Although the amount of data is very large, you don't general end up taking the bandwidth hit all at once. If you have your renderfarm set up on Azure, you could set up a plugin for your animation software, e.g. Maya, that uploads the assets for the scene you're working on and renders it on an Azure virtual machine configured with multiple processors, then download the rendered image data. One you upload the assets once, you will rarely if ever have to upload the whole lot of them again if the render management software is smart enough to keep track of which files you've modified since the last time you rendered. So you've modified a mesh but none of its textures, it only needs to upload the mesh in order to re-render.
It's hardly trivial, and for the larger shops like WETA Digital that are creating massive, virtual sets with massive, virtual armies modeled and rendered with Massive (couldn't resist :)), they can afford an in-house renderfarm -- and the costs will favor it.
For a smaller shop, that might not be so easy, BUT there are shops that are pulling off some pretty amazing animations without buying the pricey software... outfitting a renderfarm with Photorealistic RenderMan or Mental Ray or Final Render licenses can get quite expensive -- when last I checked, it was something like $2000 or $2500 per machine for a Mental Ray rendernode license. PhotoRealistic RenderMan was in the same price range.