Deep space ships also wouldn't look like futuristic planes, because aerodynamics are only needed to escape earth's atmosphere. Likely we'd be building deep space ships in space, so as not to waste fuel breaking the atmosphere. Borg cube is more likely.
Corners would suck in space unles the structure wasn't pressurized. most ships would probably be a series of tubes. They would also need to spin to allow any sort of gravity, unless we invent anti-gravity tech.
There may be parts that are pressurized tubes but cubes have more storage space than cylinders of the same size so the overall structure could be a cube.