Anybody who has some basic knowledge of the development business has a good idea of how development companies get their funding. The rough outline is that the publisher pays the dev to produce a game, and then once the game is out of the devs hands the publisher makes its money back (and pays a percentage to the dev company in most cases) through sales. This model is why piracy effects publishers more than developers - the devs already have most of the cash they are going to get for a product.
The idea is that the money the developer gets from the publisher is the entire companies budget. If the company has nothing to pitch, then they don't get paid, and as such they will struggle. This is what happened to Free Radical Design - the fact that Haze flopped mattered as little as the fact Timesplitters was a huge hit. After Haze, they had nothing - and they knew it. They most likely knew that they were doomed months before Haze was released.
This leads me onto 3D Realms. You see because Duke Nukem Forever took over a decade to make (and still wasn't finished when the company closed) and gave very little proof that it was actually being created, there wasn't a single publisher who would even consider paying them for it. Yes there were publishers who would release it, in this case Take Two, but that deal didn't include ongoing funds for production.
This is where I come to my point. Sure, maybe eleven years ago it seemed a good idea to work on a game on a "when its done" basis, but we're not in 1998 anymore. What killed 3D Realms is the fact that when the entire industry moved on, they didn't. Half Life saw the age of run-and-gun kickass come to an end, and over the last seven years or so developers have gotten into the habit of keeping their mouths shut about a project until there is something tangible there to have a look at.
If 3D Realms had put its hands up even eight years ago and said "Well, we announced the next Duke Nukem, but we haven't actually started working on it yet" rather than this whole bullshit "when its done" attitude, they might have actually had a chance. But no, you can't teach and old dog new tricks.
Before the comments about the company being small, and duke being big, have you looked at the screenshots? Unless they remade their engine every year, there is no way in hell they have been working on that game since they announced it. Not that it matters anyway, Duke Nukem Forever would have been a flop.
You see, these days shooters are a penny for twelve, and most of them are quite frankly crap. After the release of Half Life, any shooter that did not reach this general level of quality (or the equivalent for the time) was looked down upon. There are some good ones, and better, I will grant you that, but they are few and far between.
The problem with DNF is that it wasn't going to be one of these games. The development cycle for it was so long that the game itself became a euphemism for vaporware. It literally became a running joke for games that took a while to get off the ground, and then became a joke that was so old everybody had heard it before.
I do feel for the staff of 3D Realms, but to be honest, you sowed the seeds of your own demise. You dragged that one announcement out to the point where the entire games industry changed not once but twice, your product became a running joke and people stopped caring. As such, the only people who would have bothered buying Duke Nukem Forever would have only done it as a curio.
They would be the ones who didn't know how to pirate software.