Yes, it does exist. No, there are currently no confirmations on how to get it (although, again, it does exist–proof of that has been given).
My idea is it was forgotten from the Space Pirate’s Cartel Pack (as that is where it was originally rumored to be in) and is a late addition.
This, of course, opens up the idea that there could be other late additions. If you see someone selling the Forest Nekarr Cat, please contact the seller and see where they got it. Edit: Confirmed to be from the Space Pirate Cartel Pack.
and if anyone gets on on the Shadowlands, please send me it …no seriously, please. (and dwedtoof)
Edit: And to add, from the 2.0 patch notes:
“Dread Master Styrak now has a chance to drop a Kell Dragon vanity pet.”
…*sigh* at least it doesn’t sound like it is hard mode only :/