Konami has no intention of releasing the third chapter for MGS V
Definitive Edition won't include new content.
Metal Gear Solid V: The Phantom Pain has been celebrated by critics and fans since its release last September, but one major criticism is the game's lack of closure to the narrative, and later it was then revealed, that a large portion of the game, a third chapter if you will, was ultimately cut.
The fan outcry became even larger when Konami recently revealed Metal Gear Solid V: The Definitive Edition, and it was demanded that the company would bundle in the third chapter, often referred to as Mission 51.
However, Konami has no intention on releasing another mission for the game. Over on the official franchise <a href="https://twitter.com/metalgear_en/status/770652050178781184>Twitter</a> the company has confirmed, that neither a third chapter nor Mission 51 is under development, and is not a part of the collection that launches on October 11th.
It seems the game will, at least narratively, remain unfinished as it is.