I realize the conversation has mostly moved on, but I just got a chance to come back. Considering all the other changes, especially where we don't actually 'buy' are specializations, and they aren't there when you lvl up. I don't think Companion specializations just 'ding on' at 7 Eluvianus. Like I said, semi-recent thing I'm pretty sure Mike mentioned it being a story beat, not just leveling up.
I do NOT think we have to do 9 quests, one for each companion, that's a little silly. I'm sure each one has a quest or 2 for us to do that's oriented around them. But like I was saying - the story beat that triggers us having access to picking a specialization (they've said we get to see the trees somehow prior to picking) is the same thing that triggers the companions getting theres.
Way I'm thinking it might work involves a single story bit that points out we could have access to additional training, everyone does there own thing and we get to pick if we even want to. That's how it sounds like it works to me. Another thing, just from a development standpoint, but having a specialization just crop up - completely out of the blue just cause you happened to hit a level point for all your companions, but not the player is... easily overlooked. It would confuse a lot of people. If it was a story point and pointed out your companions went and got them selves additional training? Little less confusing for the masses.
As far as DAO, they already had it, and DA2, as you've pointed out they again already had the tree there. It was just a matter of looking at it and going 'ah right, lvl 7 I get access to this'.