A new Mario game was announced at the Nintendo Switch Presentation, Super Mario Odyssey. The game shows Mario traveling to a wide variety of worlds including deserts, jungles, modern cities, vaguely Roman/Greek ruins, and a candy world.
The game is a sandbox Mario game in the same vein as Super Mario 64, but with an even bigger and more open world. The game will feature Peach and Bowser, with Bowser, predictably, up to no good (although looking rather dapper). There also seems to be something up with Mario's hat, as we see it sprout eyes at the end of the trailer.
Super Mario Odyssey will be releasing sometime during the 2017 holiday season.