Kind of a bummer; reminded me of the end of Condemned ( Shaky camera, scary image, loud noise). I think there's the very real possibility that Isaac seeing the dead body of Nicole at the end of the game could have simply been more illusions now that he'd figured out Nicole was actually dead. No other Necromorphs so clearly displayed the characteristics of their hosts. You could tell it was Nicole's body once you saw it. Also the possibility of the Hive Mind surviving would be more probable since there's an announced sequel. The Hive Mind controlled all the Necromorphs telepathically so connect 1 and 1 and there's your explanation for the ending. Or she could've been real the whole time, then turns into a necromorph right at the end, only to follow Isaac onto the ship and kill him. I'd rather think Isaac lives though. That guy deserves to live.