It seems that a lot of information running around lately regarding 3D Realms hasn't been entirely accurate. Namely, it appears that 3DR is not dead for good, and in fact is still operating albeit as a mere shell of what they were before. Though 3DR as a company will continue to exist, they are currently regrouping and did confirm that the Duke Nukem Forever team was let go. So, while they may technically still be in business, one must wonder what projects they could actually hope to finish.
In addition to that, they also took the time to respond to Take-Two's pending lawsuit surrounding the cancellation of the DNF project. According to 3DR, the claims against them are grossly overstated and Take-Two's involvement wasn't as large as they claim. Further, they say that a mere $400,000 was ever paid to them for DNF development and that all the money Take-Two claims it was spent actually went to a third party. What's even more interesting is that 3DR is now attempting to blame the shut-down of the DNF dev team on Take-Two, claiming that a lack of funding on Take-Two's part is what led to the team's demise.
You can read the press release yourself and make up your own mind. It's sad that politics seemed to have destroyed what could have been a great game (even if it has been vaporware for a decade). As of yet, Take-Two hasn't responded specifically to 3DR's claims.