Brian Scott Allen
Dark Lord
I don't think what you mean is "small" extrapolation, I think you mean large or long extrapolation or even extreme extrapolation.
While it may seem a challenge in the abstract, practically speaking I cannot recall reading a book that I had a problem with classifying it as sci fi or not, at the time it was published.
So you're saying by that these genres are like porn and we'll know it when we see it?
Mythic Scribe
Mystagogue