I wouldn't think anybody will put in the time to do new Yak skins until the 3D model is overhauled. Yaks should be pretty high on the priority list though given how popular they are in the arenas. The Yaks may be the most popular of all the rides that have not yet been remodeled.
Just to be clear too, this thread is not meant to diss Warhound's skin. Back in the day when it was created I'm sure it was a fine skin. But skinners have greatly improved their craft and technique in the years since it was released, and new skinning talent has come along. Horse's Itch is just plain outclassed by many of the skins waiting in the queue to be rotated in.