With my experience...no idea. I've next to no experience with any hardcore java coding (I'm a humble weapons smith, nothing too bad there), except with the occasional code change for a ship. But with what I've seen, missions being added and even the economy mod, I'm pretty sure it'd be possible. The main issue is, as always, gameplay. A lot of ship would have to be redesigned, hundreds of new ships made, etc. New weapons as well, a lot of new stuff changed in the code.
Overall, I think it'd be a fabulous idea to add, it might make the game more immersive, but it's going to be a big hard along the way.