So if Legion is turning transmog and tabards into a tab, does this mean the transmogger on my beautiful yak will be superfluous yet again? Or will we still have to run to an xmog guy with the new tab. Will they swap out my rider yet again? Back to reforging? Something new? What do you want on your yak?
If transmog NPCs really did become null and void, it'd be cool to maybe have an Auctioneer on the Yak. I don't own the mount myself, but it costs so much that I'd say an auctioneer NPC wouldn't be too much to ask for. Unless, of course, they come up with another vendor mount for Legion and incorporate all the good mount-NPC ideas into that...
Pretty sure that the 'Improved transmogrification' will be something like D3's one, got an item? Got the mog. You'll still need to go to a special place to apply the xmog.