Will Nintendo release new Mario Kart 7 tracks?
No, because Mario Kart 8 for the Wii U has been released. They are releasing new tracks for Mario Kart 8 through download content, though.
Retro cups are the cups with retro tracks. These tracks originated or "came from" past Mario Kart games: Super Mario Kart for the SNES, Mario Kart 64 for N64, Mario Kart DS for the Nintendo DS, Mario Kart: Double Dash! for the Gamecube and Mario Kart: Super Circuit for the Gameboy Advance! They have been graphically redesigned to appear more appealing for the Wii game!
There is no such game as 'Mario Kart 2', however there have been six Mario Kart games so far; 'Super Mario Kart' for the Super Nintendo, 'Mario Kart 64' for the Nintendo 64, 'Mario Kart: Super Circuit' for the Game Boy Advance, 'Mario Kart: Double Dash!!' for the Gamecube, 'Mario Kart DS' for the Nintendo DS and 'Mario Kart Wii' for the Nintendo Wii.
The first ever Mario Kart game was released in 1992 for the Super Nintendo Entertainment System. Mario Kart 64 was released in 1996 for the Nintendo 64 Mario Kart: Super Circuit was released in 2001 for the Game Boy Advance Mario Kart: Double Dash!! was released in 2003 for the Nintendo GameCube Mario Kart DS was released in 2005 for the Nintendo DS Mario Kart Wii was released in 2008 for the Wii.
As a matter of fact, a new Mario Kart, known as 'Mario Kart 3DS' is currently in development for the upcoming Nintendo 3DS, a new Nintendo handheld capable of producing 3D graphics. It's release date is unknown as of yet, but it is likely to be released some time in 2011, possibly as a launch title for the 3DS, or maybe a little while afterwards.