According to WayForward, Shantae: Risky's Revenge Director's Cut might hit Wii U soon. The game has moved into the submissions phase in both Nintendo of America and Nintendo of Europe, and the publisher expects everything to go smoothly. The Director's Cut will come with a few extras in tow from other versions, like the Magic Mode costume, enhanced visuals, and warps.
Risky's Revenge is currently available on DSi (3DS by proxy), iOS, PS4, and PC. It was first released in 2010, and only just hit PS4 in December of last year in Europe, so this game has some long legs!