Nintendo isn't competent enough to make M rated games. If anything he's just going to do what shinji mekami does, he's going to jump from company to company, publisher to publisher and every game he makes a game it is going to have "Directed by Hideo Kojima" written on it. Kojima is too cool to be tied down, he is a nomad. A roaming super hobo.
To anyone that hasn't been informed though, Hideo is leaving Konami, but he does not own the rights to the metal gear franchise. Konami plans on making the next metal gear game, but it will not be metal gear solid. It's a new saga, so they say.