As someone mentioned in the other thread it says the 'next' MGS. So it's highly unlikely to be MGS4.
MGS5, if it is indeed in production, would be at least 3 years away. Would Konami really announce that now?
I think it's more likely an expansion like title (ie. Substance) or perhaps a new title for PSP/Wii/iphone.
Although strange things have happened in the gaming industry.








