Eredar is the name of the race. All Draenei are Eredar already.
https://wow.gamepedia.com/Eredar
"This article is about the eredar lore and the demonic eredar.
For the eredar that escaped Argus, see Draenei. For the other subspecies, see Lightforged draenei, Broken and Lost One."
As noted there, "subspecies" being things like Lightforged Draenei, Broken, and Lost One. Lightforged Draenei are a subspecies that happen to be playable.
High Elves can be considered a "subspecies" or more appropriately a sub-faction. As Ornyx noted subfactions of a race are what we actually play and not an entire race as a whole.
High Elves just happen to have the same subfaction name as their race (high elf), which can make it confusing for some as has been shown for some time now. That's why it's probably better to start referring to them as Thalassians, the name of their race in their native language.
The High Elf subfaction/"subspecies" therefore does have a possibility of happening. As has been noted by the developers themselves. Dunno about Red Eredar though, as the developers haven't commented on them in any capacity at all as far as I can recall.