Ion on Highmountain and Nightborne:
"Highmountain Tauren is culturally similar to a regular Tauren. Whereas, a Nightborne for example, is going to be much more distinct from anything currently existing on the Horde."
And this was in response to the interview's comment around 4:33 of "because the two we can play on the floor - it's like still a Tauren, right and it's still a Draenei."
Start at 4:44 to find the quote if the video doesn't start there for you.
The quote shows us two things:
1) Being culturally similar is not a detriment to becoming an Allied Race, it's not a factor that barrs a race from becoming an Allied Race.
2) Horde were given something, "much more
distinct from anything currently existing on the Horde." That is in a succinct few words:
Purple Elves.
And yes Nightborne are Purple Elves as shown here by a quest on Alliance calling you to kill "
these elves might be purple, but they're no' with the Alliance."
https://www.wowhead.com/quest=49427/...r-purple-elves
Also on that note, Alliance were given another purple elf to add to the one they already had (Night Elves). Don't believe me that Void Elves are considered "Purple Elves"? Here's proof.