The 'point' of the expansion is to stop the Iron Horde from overrunning Azeroth, not to save the people of Draenor.
Considering they tied the Mogu, Mantid and Sha up with a neat little bow I'm not expecting too much from this expansion to come back with us from Draenor but we'll see. Hopefully if it happens it'll just be a few like Yrel, because if you evacuate thousands of Draenei into MU Azeroth there's no way to avoid the whole 'hey we have two of a bunch of people now' thing.