Hideo Kojima, Konami, and Kojima Productions have dropped the bombshell announcement and have announced that the mysterious "Phantom Pain" and "MGS Ground Zeroes" BOTH make up MGS V... formally known at Metal Gear Solid V: The Phantom Pain!
Announced and unveiled during Kojima Productions' "The Core of MGS: Ground Zeroes" panel discussion, the new game utilizes the new proprietary "Fox Engine", and Hideo Kojima formally introduced the mystery game "Phantom Pain" as MGS V by unveiling a trailer that remains an enigma but fleshes out some details of what to expect of the next tactical stealth game starring Snake!
In case you missed it, here's the trailer c/o Joystiq.
The Panel Discussion and presentation is currently ongoing as of this post (UPDATE: Done now). You can check it out Live Stream via Gamespot here. Also, read up more on the story via the source post at Kotaku and IGN.