From Nintendo Direct:
Mario Kart 8: The newest instalment of the gold-standard racing game introduces an anti-gravity feature that has karts racing up walls and clinging to inverted tracks. Elements from previous Mario Kart games have made their return, including gliders and motorbikes. The game is scheduled to launch in autumn 2014 (US).
At the moment it is looking like Mario Kart 8 will be running at 60fps and looking good, the anti-grav features look like they may change up tracks in fun ways and no doubt be the source of many alternate routes.