You're all missing it. DNF is being kept in this state of perpetual development by _other developers_. That's right. There is a cabal if you will, made up of other dev teams which basically pays 3DR to keep "working" on DNF.
Why you ask? It's simple: DNF's delays makes any other game delay pale by comparison. We all know the HL2 fiasco, but compared to 3DR, Valve and GN still look like geniuses. Hell any dev team could delay it's game by 2 years and they could still say: "Well, at least we're not 3DR!"
So, almost everybody wins. 3DR gets a little stipend, other games get some breathing room. Game sites get massive amounts of hits from people lining up to bash GB every time he opens his trap. Of course we as gamers will never see DNF, but most of us have known that since about 2002 anyway.