Just this morning, I speculated in The Queue that we wouldn't be seeing larger bags in Warlords of Draenor due to the other inventory management additions in the expansion. The latest beta build may have already proven me wrong: the datafiles include the epic 30-slot Hexweave Bag. The bag requires 10 Hexweave (crafted from Native Beast Fur and Gorgrond Fly Traps) and 5 Sorcerous Earth, which is a byproduct of crafting other items.
Native Beast Fur is an item that we haven't seen as a drop yet in the beta, as not all mobs are fully itemized yet. It sounds like it may be a product of skinning, but it may be this expansion's form of cloth, too. The item being acquired by skinning wouldn't be surprising in the beta's current take on professions -- professions intermingle far more than they have in previous expansions. Note that the Gorgrond Fly Traps are gathered with herbalism. You'll either need to play your garrison wisely to acquire the materials your own tradeskills can't provide, or make good friends with people of other crafts.