Late to the conversation, but if Hollow says that they're working on Archmage, then my ever-hopeful soul will choose to believe that that's actually happening!
I've said for years that classes need more of a focus, as playing a class is far more fun than just switching between whatever happen to be the current meta armors and spamming their special skill.
Personally, other than Archmage, I'd honestly rather see them fix the stat system before focusing on updating everything else. The stat system change broke pretty much anything other than pure builds and I've lot a lot of motivation to keep playing the game until they've fixed that issue. I know it involves re-doing how stats work, especially DEX, but it needs to be finalized. The whole stat system change felt extremely random and half-finished, and it remains half-finished. I know most of the players are content sticking with pure burst warrior or mage, but for people who liked to play beastmaster hybrids the way stats work now their builds are borked.
As for old questlines, I know that they're updating the Devourer Saga and that would have been my first pick. My second pick would probably be the Dragon Wars, but there are a lot of old questlines like the old Darkovia quests, the Hall of Memories, and the holiday events that need updating as well.
While I know staff have been reluctant to do this in the past, bringing back old quests in a "time vault" sort of way (maybe the Hall of Memories again?) would be my ultimate dream. For someone who started back in 2007, there was still a lot of content that I missed out on from before my time or just from not being able to play much when I was younger. My ultimate dream would be to have the option to go back and play every quest (all that were feasible to bring back, that is) from the beginning of AQ. The world of AQ has come to mean a whole lot to me, and getting to go back to events that many, if not most of us missed out on like the wars against Akriloth, Carnax, and other iconic events from the past would reignite the passion most of us have for this game to an incredible degree.
I've known about UltraPowerPie working on Paxia for a long time, and it's good to hear it's still in the works. Paxia is what got me into AQ in the first place, even though by the time I joined it was already dead. I can't wait to see it return to even greater glory! Oh, and I know I've said it before, but please consider making class-like or subrace armor for the Paxian Clans, pretty please! :D