Being curious about these changes, I had to log in to see for myself. After taking screenshots from live servers and then capturing images from the beta, sure enough. A side by side comparison reveals that our pets with "humanoid" forms are getting an update.
Unfortunately I wasn't able to compare the Winter's Little Helper with the new version since the beta texture was broken for me. I'm also un-guilded on the beta so I couldn't take a look at the Guild Herald or Page. They both use a standard human and orc model, though, so I'm betting they will have updated looks in WoD too.
I'm not sure if the "kid" model will receive a makeover as well; the other "humanoid" pets, Argent Squire and Argent Gruntling, seem to be unchanged so far.
In any case, it's nice to see that our pets will be getting the same love as players. :)