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?