He said the same thing about DX1, although impressive, is still much less than what was originally claimed.
Really? I don't remember Warren Spector saying DX1's story was open ended. In fact, I remember an old inteview with him in which he specifically stated that DX1's story was linear. Be sure you're not confusing the publisher's claims with the developer's, because they are often very different. It's the gameplay that is open ended, not the story. But in the sequel, even the story has non-linear plot branches, which is gonna be a really big evolutionary step for FPS/RPG gaming, in my opinion.