If they are going to be added in with a full expansion (which has a much higher budget) then maybe they could hire some more voice actors for races like trandoshan etc, which speak basic but with a strong accent. I think that is as far away from human we are going to get.
Lucasarts have already said NO to wookies as jedi/sith and the "Yoda race" as playable in the past to other developers, so I highly doubt we will ever see them.
Originally they said if they wanted to add a new species it would be by expansion so a Trandoshan would get completly new start planet new voice acting and new sub quests through the game. However at this point they expected a WOW killer and not a 500 - 1mill subscription base.
Also when they first planned the game they had simple rules like no Sith Pureblood Sith Inquisotrs because it broke the law of the story and a number of dialogs. Now we have Sith PureBlood Troopers, Smuglers and Jedi Knights. We have Chiss as Sith Warriors and soon we will have Cathar as Imperials. I think its safe to say the old rules are out the window and the new rule is how much will the change cost and how much will they make from it.