IIRC both were data-mined at the same time as options for the entire model. Nothing I see about Rexxar shows me they are working on anything player-related.
A better example would be Tyrande’s model changes, or Greymane, or Nathanos’. Wholly player incompatible.
No, Saurfang model was available in 7.3.5. Straight-back orcs only appeared later in 8.0 alpha. But we did know orcs would get a non-hunched option because the developers said so in Blizzcon.
And about your NPC examples, that’s where the big Rexxar difference lies: none of them have hidden assets hinting at a unique model being the base for the NPC model.
Tyrande model is based on standard night elf female. Greymane on human/worgen. Nathanos, on human model. None of them has work done on unnecessary parts. You can’t take away Nathanos’ shirt, for example. It’s all part of their “bodies”.
One would say that Rexxar’s model is based on kul tirans. I’d take that if not for the hidden face beneath the mask. This is not how Blizzard normally does its assets. That full-detailed head got a lot of work on it, totally unnecessary if your character uses a mask all the time. And that head is exactly what you’d expect of an HD ogre (again, check ears, nose, tusks, eyes, even the tatoos).
There’s no examples of something similar being done to any other NPC. Argus (Antorus’ last boss), for instance, also had a mask that could be removed by hiding its geoset, but the head bellow was incomplete.
I don’t believe in a company spending resources where it’s not necessary. if it doesn’t mean playable ogres/mok’nathal, it at least hints at an HD update of the old ogre models.