A month after Metal Gear Solid 5 was unofficially announced, Konami has registered "Metal Gear Solid Existence" with the Japanese trademark database.
In August, outgoing Konami producer Ryan Payton let slip that Konami is working on Metal Gear Solid 5. "It'll be hard not being involved in MGS5," he said upon leaving the developer for greener pastures. "But I've got the utmost confidence that Hideo Kojima, Ken Imaizumi, and our amazing team will put together another blockbuster game. I'll be cheering from the sidelines."
Metal Gear creator Hideo Kojima is notorious for saying he's done with the series after every release, but it appears he's still on for the next game, tentatively entitled Existence.