The desire for an engineer would probably increase with the size and complexity of the ship. Is there likely to be a use for an engineer on something as small as an Aurora? And as we go up to medium-sized ships like a Cutlass and a Freelancer, then bigger Connies, then Carracks and Idrises, what do you think that progression is?
TL;DRNo crew numbers will be mandated; an Aurora pilot can handle engineering alone, a Cutlass Black is fine with one but better with two, and a Carrack should have at least two dedicated roles.
My thoughts are that... we won't put any numbers there. We want to make it attractive, which is a kind of different approach, right? So we don't go in like "this ship needs five engineers minimum to function." We really want to make it so that you as a player recognize, okay, the overhead of things I have to do is just so high, I should really ask a friend to join and take away the mechanic part of my engineering role. But since players are really interested in numbers: for example, in an Aurora, you as the pilot are also the engineer, if you are actually interested in that, because you still can go to the shop and get the repairs somewhere. You don't have to. For a ship like the Cutlass Black, I think it's also still fine that it is one person. A second person will definitely help, because then you can sit still in the pilot seat and have the other person exchange a fuse or something like that, because the space also allows it. On the Carrack, my personal recommendation would be a minimum of two dedicated roles. So you have one that basically pays attention to the entire setup, because life support is also part of that, and gravity, the artificial gravity. So there's plenty to manage, while you should have a handy person running around there and actually fixing stuff.
I want to acknowledge that Torsten is answering these questions from the perspective of the engineering gameplay. There are ship teams and other gameplay teams that all come in. It's really going to depend on what you want to do with your ship and how you want to do it. I don't think it's unfair to say that, if we're a massively multiplayer game in a universe where the intention is to have many, many people there, if you bring one person to a situation versus two people, we should be providing players with the opportunities to make two people more effective than one.
It's not even more effective, but more enjoyable. If you're the only engineer on the ship and you constantly have something red flashing and you're just stressed out and you cannot keep up with the damage that has been done... For some players, it might be fun having this stress, but for me, no. I would prefer to have someone else to rely on as well. In my head: hey, you take the left side of the ship, I take the right side.