I very, VERY seriously doubt Miyamoto will ever work on a violent FPS type game.
He said that he could make one. And of course he could. Who couldn't?
That doesn't mean that he ever would. Super-violent games aren't his style, and never will be.
Also, he has intimated in the past that the project he's working on is a bit of a side thing, a passion project, and also a "smaller project", meaning that it wouldn't be anything at all like some big "AAA" FPS type game.







