A few new spells datamined on the Patch 11.0.5 PTR suggest that older Hunter pets models updated in Battle for Azeroth may become available again!
These new companion spells are thought to be related to the return of old models.
As part of ongoing modernization, Blizzard updated several creature models with the release of Battle for Azeroth, including many long-time hunter pets. While the new models are less blocky and higher resolution, some players were not so satisfied with the changes to their long-time companions.
The new models are improvements, though not everyone was happy with changing their long-time companions.
Exactly how this may be accomplished is as of yet unknown, though we presume this will be some kind of opt-in switch, rather than simply adding the old models back into the game world for players to find and tame.