Sargerai only exist in the alternative-timeline (wOD) where Draenor is still in the past and intact. Several lore pieces state that things there work a bit different from the main universe.
So, no, not in the main universe/timeline.
Edit: But you raise an interesting point:
I think that, IF (a big if) an Eredar would betray the Legion, maybe (maybe) they could be elligible for Demon Hunter training. Maybe after that, the Draenei Eredar would accept them in the Exodar.
Maybe.