I am an idiot. This was announced not that long ago and I completely forgot! My apologies for that.
Shantae: Risky's Revenge may have originally released as DSiWare, but it seems that the title could be heading to Wii U in the future. In a Famitsu interview, it seems that WayForward's Matt Bozon confirms a port of the game to Wii U. Taking things a step further, Japan never saw release of Risky's Revenge, making a Wii U port the first time the title saw life in that region. Let's hope the port also sees release worldwide!
We've reached out to Mr. Bozon to get confirmation on this information. We'll update the post as soon as we have those details.