It sounds like gunsmith is coming back, they mentioned it in the following Developer Q&A:
4:34 is the answer to customization in-game.
Dominic Butler (Lead Game Designer) says: "You'll have a lot of opportunity to change your physical make-up, as well as the kind of outfits, the cloths you're wearing, the equipment you're going to bring into the field..." and then continues to say "... but also different weapon types that can be augmented with a multitude of different attachments".
Nouredine Abboud (Senior Producer) then goes on to talk about gunsmith specifically with a comment of "you'll be able to deploy the power of gunsmith to the other components of the game".
So it's not really a "confirmation" that gunsmith itself is in the game, but it sounds like it might make a reappearance or at least something based off it will be available.