I'm not sure how many people here have played a C&C game, how many have actually played a true C&C game pertaining to the Tiberium Wars, and how many people actually liked the games (C&C3 doesn't necessarily count).
What I was thinking was since GDI already has begun to enter space, what with (possibly) interstellar missile capability and stations in space (albeit the Philadelphia was destroyed, but the fact still stands), The Brotherhood of Nod, being as sneaky as possible, has begun to work on their space-faring skills, especially with that darned Ion Cannon foiling their plans. ^^ Of course, C&C has not progressed to the point where ships and intergalactic warfare would be possible, so maybe we'll move time up past the Third Tiberium War maybe 30 or 40 years (2142 would be roughly 82 years, for those who like EA connections).
I know, I know, if we move time forwards, military doctrines and ideas may change, resulting in a drastic shift in ship design and firepower. Who knows? Maybe Nod will end up will the huge, god-moddy ship, while GDI will take it down with 150 smaller, more manuverable ships (a la Revolucion).
Now for content:
Provided military doctrines and designs wouldn't change in all that time, all factions (perhaps including the Scrin, which of the three would be the easiest, since [I think] we see their ships in C&C3) would have their buildings designed in their motif.
GDI would have their signature gold and white and possibly blue structures all blocky and industrialized, with slower build times than the other two factions, but with massive, pompous, belligerent ships. I suppose GDI would be the least technically advanced of the three factions, but with only an empiric margin between NOD and GDI. The same would be for ships. Since the UN cut funding for the GDI, they've been shying away from the more advanced tech, to more conventional stuff. In space, that might not cut it, so it could be back to sonic pulses and advanced lasers for them, to keep up and to keep balancing issues straight. We could implement an autocannon like system for GDI, or we could maybe do a sort of Minmatar-Caldari type of tech, like from EVE. Relatively weak in the beginnig, but packing a hard punch later ingame.
NOD would have their infamous Red and black motif (with color accents depending on the player's color) on their quasi-organic looking ships with their colonized planets having a darker tone to them. I was also thinking about the voices of the units. obviously, Nod would have a sort of... brainwashed, blind follower sort of tone. I suppose we could rip voices out of ther previous C&C games (a LOT of stereo mixing). The Nod weapons would be the standard beams and weird design, like the Nod Obelisk. Nod traditionally is a guerilla warring faction, so fast, light attack crafts for true hit and runs on planets and on blockades/enemy formations.
Scrin...
Hmm, I'm not too sure how we'd go about with the Scrin. Anyone who's played C&C3 should input ideas for design about the Scrin.
This is all speculatory, but I think this mod could be really good.