Konami have announced that the prologue for Metal Gear Solid V: The Phantom Pain - Ground Zeroes will see release on Steam (PC) on December 18.
Konami also confirmed that the game will be "4K compatible and will feature an increase in the number of simultaneous light sources, the number of models that can be displayed on-screen, and increased shadow resolution".
Sounds like the ultimate edition of the prologue in other words. No pricing on Steam has been announced so far.