2013 will be the year that Metal Gear Solid fans get to experience both Metal Gear Rising: Revengeance and Metal Gear Solid: Zero Grounds.
However, the title everyone is waiting to hear more information on is the next installment in the main series: Metal Gear Solid 5. Konami has not made many mentions of the upcoming title, but IGN asserts their recently revealed The Phantom Pain is a code name for the MSG 5.
The Phantom Pain was announced on Spike TV's VGA event which would be produced by a Swedish developer called Moby Dick Studios. According to IGN's Collin Moriarty, "the game's logo has some mysterious lines on it and leaves some other strange gaps. As posted by NeoGAF member Sn4ke_911 in this thread." He even asserts that the words "Metal Gear Solid V" fit perfectly among the lines and gaps.
To further substantiate his hypothesis, Moriarty notes that Moby Dick Studios' website is a fake. Details on the creation of the studio's website indicate that the owner is well hidden from public view. VG247 also questions the validity of the website. Furthermore, reports indicate that the studio will actually be called Joakim Mogren which is supposedly the most significant of all the clues. Joakim is an anagram for Kojima, which is the last name of the franchise's creator and Mogren includes the word "ogre" which was the code name for the next Kojima project after Zero Grounds.
Finally, there seems to have been a number of people from Konami wearing Moby Dick Studios/Phantom Pain T-Shirts according to a tweet from Alex Rubens. Konami is the long-time publisher of the franchise and further substantiates the aforementioned claims.
To add fuel to the fire, Moby Dick Studios has recently revealed a series of screenshots for the title which could add more credence to the MGS 5 theory. A man represented in several images has a great deal of similarities to franchise protagonist Solid Snake.