I've been mulling about on an addon idea I had for my Keep of Metal and Gold mod, a cyberpunk mod a la Deus Ex and System Shock. It'd work off the same power, but its stuff would be high-tier, endgame stuff including generating power thru micro-singularities and cybernetic body modifications.
Becoming a swarm of nano machines could be fun.
As for a space mod there are very few ways it could work with the limited minecraft mechanics.
One method makes space as just one singular dimension with planets represented as block structures in the physical world and you would need to navigate your spacecraft near the planet to load the world.
This would have you flying around searching aimlessly for planets much like crossing a 14k block ocean in the current BoP world gen.
Another method would utilize the generation of multiple worlds and would probably fill up your disc space pretty quick. It would most likely work as follows. When you leave the planet a world is generated to represent your solar system. You can travel near any planets within and you would be able to go to them. One block of your space ship should be something called a navigation console anyone using this should be able to set a jump destination to which you can travel to if your ship has a warp drive. Each time you jump to a new system your navigation console should be updated with a list of new nearby solar systems and also contain a larger map to plot known systems.
Now implementing random solar system generation would be rather difficult with this method but random planet generation within could be do-able. Coming up with tons of new unique textures will also be hard.
No matter what you do, the world files that generate with this mod are going to be huge, and when worlds are generated for the first time things will lag hard.
Yet another method is to use what galacticraft is using which is a system of menus, which will in-turn save disc space by not having to generate the space in between worlds. It's a give and take.