At least, I hope Namco will mention it/do something next year, for the 20th anniversary of the game (gt6). Let's dream...
Hmm, if the game is to be on Steam, we might have to buy a special game controller to help emulate the arcade experience. The only controller that I think can emulate the turret motion is the Razer Hydra.
Here's the controller:
http://www.razerzone.com/gaming-controllers/razer-hydraLooking into this, they never mentioned anything about having a frame and mount for turret-based motion. So, I'll just hold off on the Hydra until they have attachments geared towards the rail shooting rarity among others like it.
Another method of emulated control might be lightgun/guncon technology. Wherever you aim on the screen, the cursor/crosshair is aimed on that spot. Precision is always dependent on the monitor's size. It's possible to use a projector for greater precision, but it might require time to setup and calibrate the "Guncon-GT" (The GT can either mean Galaxian Theater or Galaxian Turret). And if you plan to recreate the Theater at home, Valve might partner up with Namco-Bandai to provide a GT-6 Home Theater Kit, which might come in packages from the bare minimum needed to recreate the gunner stations, to more complete, yet expensive packages that can take up an entire room. Before you go any further, no, the more expensive packages probably will not include building an exact replica of the theater, rather the premium kits include what the original theater featured in terms of AV systems, just without the hassle of Laserdisc tech, since the game will operate directly from a PC via Steam. I'm talking about a sound system powered by Bose, and a video projection system powered by Sony or Panasonic. Now, if you find it cheaper to buy the AV equipment separately, Namco-Bandai might provide a list of recommended equipment for the game, even those branded with THX Certification.
Long story short, if they do release Project Dragoon on Steam, unless you have the resources to emulate the theater at home, you're better off with a mouse to aim and fire.