However, a few months ago the Duke Nukem 3D source code was released. Since Dark Forces runs on the same engine, there is hope yet.
I'm afraid you're wrong, Duke3D used the "Build" engine, while DF used the "Jedi" engine developed by LucasArts.
There were rumors at the time of DF's release that they had "stolen" the Doom engine code, but I don't think there was anything to them (obviously, or Id would have sued). Of course that would have been silly anyway, since there were other games that used the Doom engine out and others that didn't long before DF came out.