Disagree.
I don't see the business case for this. I mentioned a while back that, if Nissan did this, they would be doing it exclusively to artificially price-stratify the lineup since it's the same engine (minor differences aside) in a different state of tune. I think that would be a poorly-received move. As many have noted, we aren't getting a $30K Z. We just aren't (or the odds are astronomically low). So I don't buy the argument that this offering would open things up to new buyers further downmarket. It would look pretty cynical for Nissan to show that they can offer a Z for, say, $35K with the 99% of the same hardware as one that they choose to offer for, say, $40K. Or if they strip away virtually everything else in addition to the lower-spec engine tune, what will we be left with in that "base" model? Think of how de-contented it would have to be in order to make this not look like a cash-grab.
If anything, placing the 300HP tune in any model in the lineup will only serve the purpose of asking potential buyers to pony up more cash for a less powerful Z than the current Z34 that's been in service since dinosaurs roamed the earth. This seems like a backwards step.