The concept is very interesting to say the least, however, the sheer number of the ships that should be converted for this to work may become a hindrance. Therefore, based on a similar proposal I read on "Free skies" mod, I think the "think big, yet start small" approach that is advocated here,
I certainly don't think that the mod has been abandoned (judging by the bumps, there seems to be a healthy amount of interest from the community), but I can see people not really wanting to put in work on it while there are still so many pieces missing. Artists may see it as risky to sink time into a project when the code for the basic mechanics of the thing aren't in place, and coders don't really have any assets to work/test with at this point, so it's understandable why progress is slow given the number of other, more established projects that their help is needed on. That said, I think a viable modpack might be more within reach than it seems. I'm not saying it isn't going to be a lot of work, but here's a (fairly modest) list of things I think would be needed for a bare bones, generating interest type of release:
- 1-2 fighters
- 1-3 weapons (50 cal machine gun, cannon, flak turret?)
- 1-2 airships (either armed or unarmed)
- flugstein mine (really just a black sphere)
- weapon, engine, cockpit, and damage sound effects
- visual effects for bullet impacts, explosion and/or flak
- couple of HUD tweaks
- handful of music tracks (main hall, briefing, ambient, battle)
- 2-3 missions (defend your airship, minefield escort, attack the enemy convoy and escape before reinforcements arrive)
- appropriate main hall and loading screens
- 1-2 skyboxes
- ocean?
Obviously there are thing's I'm forgetting, but that seems fairly comparable to the very successful BtRL demo release (though they did have lots of polish, VA, etc.). I've intentionally left off the significant code/scripting changes that atmospheric missions require (mostly AI problems as I understand it), but I'd guess that there would be a lot more code-side interest in working on those issues if a mod like this got to a point where that were the main thing holding back a release. I'm willing to bet that a good number of the items I've listed can be salvaged in one way or another from other sources. For instance, mods like TVWP and 158th used machine-gun type weapons--why not build off of what they have already accomplished (giving credit, of course)? Historical photographs or just random shots of flying through the clouds could be used for the main hall and loading screens. I have a white smoke effect I made for FotG that would work for a damage trail, and I suspect that community members have lots of similar stuff (skyboxes, visual effects, sounds) laying around that could really help speed things along, even if most of it ends up getting replaced once the mod gets on its feet.
Anyway, just thinking out loud here; hope my 2 cents are of interest 
lostllama, do you have any screens of the airship models you've acquired?
or something of a sort is sought. Start off with a minimum number of fighters, and larger ships (your choice on what should be included, I'd choose something along the lines of the proposal of "swashmebuckle"), and make 2-5 missions that are ww2 inspired, "battlegroup defense", "battlegroup attack", that sort of thing. Fluff from the wh40k universe is good enough for that sort of missions, I think. This will serve as a demo and also as an invitation for more talented modders to join in.
There were too many good mod attempts that never made it, simply because the modders involved either got too ambitious and then got tired and left, or simply because they never could muster enough personel to make it past the difficulties involved in modding, from FRED to everything else there is and it would be a waste, since so much of the work (modelwise) has been done already. Besides, making a model work with Freespace 2 isn't the easiest thing in the world. Therefore, for the beginning, keep the number small. There are those who might suggest that the fluff of Battlefleet Gothic is only about big ships slugging it out, however, let's not get too caught up in the small fry. Remember, it's just a table top game's implementation on the PC. The purpose is to have fun. Those who might not like the direction you take your mod, might as well remember that.
I think that everyone has their own opinion of what the mod should focus on and look like, I have mine. Deployment of huge fleets of ships slugging it out from far off, with swarms of fighters out to destroy enemy bombers and protect their own bombers, who would both paint targets for the big ships of their side to shoot and also kill them off outright, (the bombers that is). Fighters and bombers' actions (that FS2 basically is) in WH40K: Battlefleet Gothic should be interesting to fight, however, care must be taken so that they are never shown out of proportion, because they are too small to do much harm to the big behemoths slugging it out. They shouldn't be made into superfighters or bombers that could destroy a dreadnought with one bomb, it would take tens or hundreds of them and their purpose should be to put a critical subsystem out of action, instead (for the largest ships, at least). Alternatively, to kill of a dreadnought, would take many missions and many bomber wings converging on this. I sincerely hope that you actually make something playable in FS2 open out of all those beautiful models. Like I said earlier, starting small, produce a demo with 2-5 missions with just a few fighters and bombers and ships from each side and build on that in small steps. That's how most mods that actually did make it, did so.
