Found a little bit more news to fuel the fire here, Bank of America/Merrill Lynch car wars analysis forecast just came out and while the main parts of the article are about the upcoming mazda3 they do mention redesigns of the GT-R and Z as coming out in 2017, here's the link to the article for anyone who wants a quick read:
We Hear: 2015 Mazda3 Accidentally Revealed? - WOT on Motor Trend