The one thing that left me a bit confused/concerned was this from the Q&A:
Will companions be interchangeable during long rest?
Yes, at the start of your adventure your recruited companions will be at camp when not in the adventuring party, and can be swapped in and out at camp. Just like friends in real life! After the first act however you are going to have to commit, also just like in real life.
That very last sentence is what has me concerned.
Why does it concern you? Personally, I dislike the Get-them-all feel of most modern RPGs - while BG1&2 didn't exactly block companions you did adventure with the party, I did generally stick to certain party composition. I still do so in modern RPGs (PoEs Kingmaker) with other guys only joining for quests. I find it somewhat cheap that one can experience "everything" while not actually not using companions. I didn't really know Kana, Hiravias or Takehu until I traveled with them for the majority of the game. I don't mind having to commit more.
That's one of the things I liked in D:OS2, though they could have done something more interesting with it. It sounds good to me on paper - we have one chapter to explore companions available to us and form the party for the adventure. And if companions are good enough then subsequent playthrough would feel more different, then "you got everyone" approach. It would be cool though, if non picked comanions would still be in the game in some form - perhaps join enemies or get turned into mindflayers and such.