We wouldn't know, you'd have to ask Nissan HQ or maybe an insider on that.. However, the newest Z that's been out is the 2013, which got a facelift just recently. They offered new things in the existing sport package, such as shocks, red calipers, and new style of rims. Oh, and their front end, they removed the fangs.
You'll definitely get at least 2 years in
my opinion.
And if you do get to find an insider, ask him for some hot stock tips!