VI and PI were valid codenames as of last year (only in short form), I personally never heard of updates since then.
Right now, speculations remain speculations as these two are way too far from taping out. The shift to 20 nm fits the timing, but I am not so sure on the gate-last part. One have to consider die-stacking and GlobalFoundries' recent announcement and the developments of 14XM FinFET (eXtreme Mobility) technology for mobile applications in 2014.
The shift from 28 nm to 20 nm would give theoretical transistor scaling of 0.51x in die size, and 1.96x transistor density. So a 650 mm˛ (with 8.5 Billion transistors) chip made on 28 nm could end up 335 mm˛ or even less on 20 nm. [Disclaimer: Different scaling factor for logic and SRAM was omitted for simplicity
That would probably be enough to make something like this:
(Nevermind what's on the image, it's irrelevant to the topic of PI and VI