Miyamoto has stated in the last year or two that Mario Kart as it exists in it's current form is where it will stay, as it is highly successful and doesn't require much meddling in the game-play mechanics.
Mario Kart 8 will be a natural, predictable extension of Mario Kart 7. Gorgeous HD visuals thanks to the Wii U capabilities, Off-TV Play, robust online multiplayer, tons of racers and courses, and some tinkering/improving/iterating with the hang-gliding and underwater elements. Don't expect anything beyond that, or you will be disappointed.
Mario Kart is so popular because it knows what it is and it keeps things simple. Playing it safe is the best thing they can do to achieve high sales and the much-needed cross-over appeal to casual players just like Mario Kart Wii.
The Screamapillar is easily identified by its constant screaming—it even screams in its sleep. The Screamapillar is the favorite food of everything, is sexually attracted to fire, and needs constant reassurance or it will die.
