It's the same in Legion. Crooked and I were comparing his follower a while ago and the difference was huge. The top one is my view, the bottom one is his view. I think it came up because I was saying "Look at how red your follower's face is!"
So I have Broll, who for me is always in his night elf form. I like having him around he makes me gold and resource when I'm doing my world quests. And he tanks - I AM NATURE'S RAGE! - and he used to be highly amusing in those free-for-all PvP world quests because he would ALWAYS attack Kyxyn.
But everyone else gets to see him in bear! And when I'm running around he goes in travel form!
This is the one time that I wished that my view of the follower was what everyone else sees of them. I wonder if he's in cat form for everyone else when I am stealthed?