Quote from FrieChampIf that post by a former employee is true, then that demo was nothing but scripted sequences. There was no game in 2001...but that doesn't really speak for 3DR either does it?
The same guy that wrote the "Chair Story" said that it was set up for an e3 trailer, but for most of it it was actually in-game content. The vehicles were working, the shooting, etc. All the dialog was all written and recorded just for the trailer, but the environments, models, weapons etc. were actual completed/in progress, working stuff. In the hands of any competent company it would've been done and out in 2002 and it would've been great and made more than enough money for Duke 5 and more.