Can a publisher like Konami really let go of a franchise that has generated as much revenue as the Metal Gear series? The obvious answer is "no" and it seems that the people at Konami are laying out the framework needed to continue making Metal Gear games, even if they do not feature long standing protagonist Solid Snake. With or without him or Hideo Kojima, the chances of seeing another Metal Gear in the future are high.
Ryan Payton, who was assistant producer on Metal Gear Solid 4: Guns of the Patriots, declared that the developers see "still a lot of room for filling in the gaps as far as Big Boss is concerned". And where some see gaps in the story, Hideo Kojima perceives prequel and sequel opportunities. In fact, one could argue that the whole Metal Gear Solid 3 was a long exposition regarding the possibilities of the franchise in the absence of Solid.
Confronted with a question regarding the possibility of a sequel being in the works, Payton said that "There are some misunderstandings that this is the final Metal Gear game. But it's really the final chapter of the Solid Snake story. That's all". And even if Hideo Kojima really leaves the franchise after this last Solid Snake adventure, there's always the possibility of another director taking over and creating the same universe. Such great money generating franchise cannot be abandoned.
Ryan Payton also talked about Metal Gear Online and said that "We're working on a handful of new maps, skills, and rules that we're bug checking at the moment. A lot of the stuff is pretty far along". He hopes that the MGO players will get more out of it than those playing Call of Duty 4 online because of the way the developers plan on releasing new maps and modes as soon as the players tire of the old ones.
Metal Gear 5 Might Be Prequel
Will not feature Solid Snake
... so hot right now