An anonymous poster on 4chan is claiming to be 1 of 20 employee’s at the Konami California branch that has been fired and is now answering questions about the game. He claims to be an MGS fan and therefore will not spoil the ending.
Leaker claims that the game is 80% finished and AI had a lot to due with the game being delayed. The release date will be announced at TGS 2014.
Keep in mind these are not official informations, and therefore are not necessarily true.
If you wanna see some details, check the next page. There are minor gameplay spoilers ahead, the Story related spoilers are deleted but can be seen in another link bellow.