Even WoW is adding this feature with Legion. I think it's eventually going to be implemented in this game especially with how it's being pushed by the community all the time. The question is when. The answer is "not anytime soon".
If I was leading the dev team, I would try to milk the current system + selling retainers for as long as I can (even though as a player I find it pretty revolting) because this is a pretty big and expensive feature to implement. Definitely expansion material.