Soundwave on 19 November 2013
I'm pretty sure "Super Mario Galaxy 3" is coming for November 2015. It's probably already in development at EAD Tokyo as we speak.
Miyamoto going out of his way to stress that 3D World doesn't mean the end of the Galaxy series was basically as much confirmation as you're going to get (see: Miyamoto saying wouldn't Pikmin look great in HD well before Pikmin 3 was officially announced for Wii U).
