You sure? That seems REALLY odd. The N80 is a pretty new body. I was under the impression that it replaced the N90s.
The N75 doesn't seem like it is much of camera in comparison. It has more metering spots, but no mention of DOF preview, or much in the way of manual control options.
And I could find no other mention of a discontinuation.
Of course the WEIRD thing is that the D70 uses the N80 body. As does the D100. The N75 seems to be ab it different.