Kojima Considering New Metal Gear Spin-Off Starring The Boss

Considering that Kojima's original plan for Metal Gear Solid 5 was to have his younger development teach create a game about The Boss during the invasion of Normandy, this isn't exactly surprising. Rising was created as a stopgap for him to try to hand off the franchise to a new generation of Metal Gear developers internal at Kojima Productions without having to worry about a numbered game in the series (incidentally Peacewalker was also at one time considered to be MGS5).

With the core story of the different Snake's essentially wrapped up with MGS4, Kojima can really only go backward unless he rewrites Metal Gear history even more (Peacewalker essentially leads almost directly to the start of the original MSX Metal Gear, with the construction of a functional Metal Gear at the end of the game, and Mother Base growing into what is almost certainly the original Outer Heaven). Ground Zeroes will probably cement that further.

Kojima could probably continue the trend indefinitely backwards though time. A game about The Boss could lead to a game set in WWI about Major Zero, and to whomever his mentor might have been, back through recorded history. Standing in as Metal Gear, you could always have a weapon capable tipping the balance of power too heavily in one direction or another.