During today's Nintendo Direct, it was announced that a new Sonic game is coming exclusively to the Wii U and 3DS, called Sonic Lost World. This is part of a worldwide partnership that Sega and Nintendo have entered into, so I'd expect to see a lot more Sonic on Nintendo's systems in the near future.
Will Sonic Lost World have dinosaurs in it? Chances are, no. Should Sonic Lost World have dinosaurs in it? Heck yes it should! More details about this game will come before E3, so we'll just have to wait to find out if Sonic befriends a Stegosaurus in his upcoming Nintendo-exclusive adventure.