I'd like to see a bit more of companion interaction and bonding personally. I absolutely love DOS2, but the whole "Only one can be divine" never really clicked with me as I much prefer being friends with my... Friends. Sure there is an option for everyone to "live happily ever after", but it isn't really a choice when it's only one choice.
Part from that, most of my wishes are already in some nature mentioned already. I do however, would like skill / stat progression to not narrow you down so much. For an effective character (playing legit without trainers or mods), you can't really focus on more than 1-2 skill trees (pyro, warfare, etc). I myself have always liked playing hybrid characters, mixing a bit of everything to create my ultimate pool of skills and utilities.