Hmmm. I've always believed the story loses impact with Deckard a replicant. Also it forces the viewer to speculate—e.g. why is Deck weaker & slower than the other reps; why is he allowed on Earth at all? Leaving open-ended questions, or multiple interpretations is fine, but I don't think compelling speculation is good story-telling. Why does Olmos's character make a unicorn while Deck dreamed of one? Coincidence? (& there I'm speculating again, lol!).