2018 could be a short year as well for the LEAF with the 2019 car and its variants arriving in dealers lots in November/December of 2018.
You seem to have a better handle on Nissan than most, so you are probably right. If so, I will be disappointed. I was hoping that "second half of 2018" meant the middle of 2018 FY, which starts in October. That's a normal time to introduce the next model year anyway. Of course, we're only talking two months. I just hope that the tax credits are still around at that point (both federal and NYS).