Metal Gear Solid 5. This is at the top of our list of what we expect to show 
up at PAX Prime 2012 and here is why. Kojima is expected to do an 
introspective on the past, present, and FUTURE of Metal Gear during a panel 
at PAX Prime. We have already brought up the possibility that Kojima is set 
to reveal Metal Gear Solid 5 during PAX Prime, but now we are almost certain 
this will happen.

On August 30, 2012 Konami will reveal the Fox engine and apparently "shock" 
the gaming world. Nothing will shock me more than the reveal of Metal Gear 
Solid 5 running on the Fox engine. Two day's later is when Kojima will do 
the introspective on the Metal Gear series, and I will not be surprised if 
the Future of Metal Gear is what's being teased for the August 30th event 
being held in Tokyo. We will be at the PAX Metal Gear introspective to give 
our impressions on the event so stay tuned for more.

http://www.dualshocknexus.com/2012/08/two-possible-shockers-at-pax-prime-2012.html