The Archer needs a bit more in the Constitution or the HP department or something else because his lack of Stealth does make him far less appealing in terms of Rogues in higher difficulties. That could just be a baked in bonus similar to the HP on hit of the Reaver or the Guard on Hit of the Katari. Alternatively you could give him some sort of alternative resource to defend himself such as Guard or his own variant on the coins that make Isabela so appealing.
Can we get some of the powers of the Templar altered to make her more of a DA:O Templar and less the Seeker re-skinned Templar of DA:I? Templars don't strictly deal in demons, they deal in caster control and Spirit damage. The new version of the Templar has "Seeker" branded on her forehead because it's Cassandra's build and it was altered because A.) She's a seeker and B.) Enemies no longer have mana to burn off. Her 'wombo combo' is extremely awesome but its the only spots she gets Spirit damage.
The Duelist has a very unique system that allows her to defend quite easily so her lack of Stealth isn't a problem. I would bring the cost of her Bolt down based on the reduction in damage that it took a bit ago. I would possibly increase the damage on her lower tier powers because I see very few people bothering with more than Broadsides (even post nerf).
Now that we've gotten so many difficulties I could see removing Challenge for War Cry on all Warrior builds that get it and possibly adding a taunt mechanic to the Avvar's bottom tier power (Rage of the Avvar) that grants him guard already. If not removing Challenge for Warcry you could remove one of the powers less used on the given Warrior builds.
The Assassin and Hunter should lose Hook and Tackle for either Gangway or their own version of it, the dual power is extremely useful because it can get you in or out of combat with ease.
I have quite a few other ideas but this is a short wishlist.
Add a 3rd ability tree and increase the players level max from 20 to 30.
I would agree with a third tree with or without a level increase. I would love to see a tree that changes the play style of the older classes more than I would actually want to get newer classes.