While I’m a playable Horde Saurok supporter, I figure what I have to say would be fitting here since I do also have an interest in Sethrak.
Ultimately, Dracthyr, while a neat race, doesn’t really fit what I want from a reptilian race.
When it comes to fantasy, lizardmen are my favorite race. They’ve been something I’ve loved for themes, aesthics, culture and such. From Iksar in Everquest to Argonians in the Elder Scrolls series, I’ve always had a fondness for them and wished that WoW would get a playable Lizardman race. With Saurok, they have a lot of potential to get expanded in many ways, with a great backstory, a blood sworn enemy with the Mogu, and many typical Lizardmen themes and aesthetics that could be applied to them.
Dracthyr are pretty cool to see, but I consider dragons to be much different from Lizardmen races. Moreso with Dracthyr having a humanoid form, so it’s not something entirely reptilian. I’ve considered dragon related races, like Dragonborn in D&D, to be a lot different than Lizardmen when it comes to mechanics, personality, and culture. They’re all awesome races, but don’t really do it for me when I think in terms of Lizardmen races and my personal preferences.
This isn’t a dislike of dragon related races, but more of my own personal preferences. Some people like Wood Elves, some people like High Elves, some like Dark Elves, and some like Half Elves. Sure, they’re all Elves, but there is a lot of differences between them. It’s something you could apply to reptilian races in general, as there are differences between Dracthyr, Saurok, and Sethrak.
Not to mention that Dracthyr are locked to one class, which while it has two specs, doesn’t quite feel great since playable races usually have a choice between several classes. Sethrak and Saurok would be capable of choosing between several classes, as well as having different cultures, personalities, storylines, and so on that would have a different feel from each other.
My hope is that Dracthyr won’t be considered the definitive reptilian race or act as a compromise for those wanting Sethrak and Saurok. I personally think that all three could be playable and be completely unique experiences. After all, Night Elves didn’t prevent Blood Elves from becoming playable, and they are completely different in many ways. Moreso when considering Nightborne and Void Elves.
If we’re capable of having multiple flavors of Elf, Dwarf, Human, Gnome, multiple clans of Orcs, and so on, I don’t see why we couldn’t have multiple reptilian races. There are differences between dragon races, snake races, and lizard races that would add a lot to the game. I hope that both Sethrak and Saurok will be considered in the future because of that and will both become playable. The more variety on that character creation screen, the better.
I hope to see more reptiles on that character creation screen! 
