I don't expect much in the way of changes to mechanics that some of us would consider problematic, so I'll just limit this to actual new content for the sake of space.
- Additional feats
- Barbarian or Bard (since Larian may not have figured out what to do with reactions and metamagic yet, so I don't expect Monk/Paladin/Sorcerer until way later)
- At least one new companion, preferably the Druid. Their interactions and immediate story relevance would probably make them major enough for them to be the centerpiece of a patch by themselves, and would require a fair amount of testing. I have zero interest in rolling a Druid MC, but would be highly interested in a companion Druid.