I would personally want to see in Pillars of Eternity 2:
1) Add on (yes, there will be atleast one, that is promised and allready payed for for some of us) with: Story what have something to do, something to add, for orginal story. Making storyline deeper and more meaningfull. After all let's say a decade after when people will buy this game they get ALL of it, including modules what are made bit later.
1.5) IF we get more companions during this add on I wish and hope they have something to say/give/do/interact during mainstory / game. Not only for new content.