I don't like that Scott gave a definitive answer either - the ambiguity adds so much, as you say. Though I prefer the answer to be "probably is", rather than "probably isn't" (based on the Deckard unicorn dream, unicorn in JF Sebastian's apartment and unicorn origami sequence)!
Well now. Nexus-6 have a pre-defined lifespan of 4 years, sure. You also kill them if you try to extend it by any means. What if Deckard was a -7 or even a -8 (both mentioned ages ago by Scott as in his vision of the universe) though? Sammon postulates -7 would have a normal human lifespan...
Like you, the original is probably my favourite film, so I'm similarly nervous - slightly disappointed it seems to have stopped raining.
Scott is on record as saying that Deckard is a replicant, so, given he's the exec producer and given the stand-off between Ford and Scott about Deckard's...