Honestly I think that it would totally be fair to make a paid DLC that gives every class one new subclass, maybe with a couple races thrown in. The amount of time and effort that goes into those from a mechanics andwriting perspective is enough to justify it. I doubt they'd release subclasses or races or anything like that one at a time though. I think new side stories are in an awkward place due to the level cap. Any extra side quests they include would just disrupt the xp curve of the game and lead to players hitting max level sooner, which isn't great when there's not much flexibility in the level cap.
