Devs usually hyper-polish a small slice of the game for E3 demos. Just because it is far off doesn't mean that it can't be real. Trust in the Naughty Gods. They know what they're doing.
One of the ND devs was on Giant Bomb at E3 and spoke about the demo. He said often times with those demos they're putting systems in that they want but that might not ultimately make it in the end. But what's unique about that Part II demo is that they didn't have to do that. They assembled the demo from systems that are already close to a shipping state. He ends up saying that it's not something that's going to be thrown out, it's what the game is going to look like.