Metal Gear Solid 4 isn't even out and whaddaya know, the game's creator Hideo Kojima is already thinking about Metal Gear Solid 5. While MGS4 was supposed to be Kojima's last entry the series, he seems to have had a change of heart recently. Isn't he ready to move on to other things? Dunno. What we do know is what he told Famitsu [*spoilers ahoy!*] :
I gotta start thinking about MGS5... Even though, well, Snake's story ends in MGS4.
...About MGS5, that would be something that Kojima Productions would have to make, I think.
Sounds like Kojima's at least considering doing Metal Gear Solid 5. If MGS4 is a hit, it'll be hard for him not to do it. And hey, if he actually does make MGS5, then he can think about making MGS6 after that!
Famitsu scan below.
Kojima Is Thinking About MGS5 [My News Flash Blog]