20 months is way too early. The seventh generation consoles are just getting started and are bound to have a lot more revolutionary titles coming out soon and in the coming years. I am hoping that there won't be a next gen console sooner than 2012.
Currently Playing: Mario Kart 7, Mario Kart 8, Luigi's Mansion: Dark Moon, The Legend of Zelda: Majora's Mask, Super Smash Bros for Wii U
Predictions:
Super Mario Galaxy will pass Super Mario 64 in total sales CORRECT!