I suppose I am ready to submit my guess at the new engine lineup for the upcoming Z35.
Base: 2.0L Turbo 4 cylinder from the newly announced 2016 Infiniti Q50:
2016 Infiniti Q50 gets 2.0L turbo four
Upgrade: 3.0L Direct-Injected Twin-Turbo V-6 from the Infiniti Q60:
Infiniti Q60 Concept previews sexy styling, twin-turbo V6
There will be no hybrid, as this combination is too heavy, hard to package, and expensive for a vehicle like the Z. It will be saved for the flagship technology demonstrator, the GT-R.
Thoughts? Hope I'm not stating the obvious here.
As for naming, you could either go with just 'Z' and 'Nismo Z', or you could do the old 200ZX, 300ZX, and 300ZX Nismo. I don't know if I care either way.