Why would anyone spend money to bring a game to a system with a userbase of maybe 4 million by the time this game comes out? Especially when many of those customers are already buying MarioU and NintendoLand. And especially when the game is a sequel to a game that I don't think sold particularily well. If was a 3rd party I wouldn't look at WiiU until fall 2013 unless I had a franchise like COD, AC or Batman. Or something the WiiU audience will really wants like Monster Hunter or Scribblenaughts. Games sold to WiiU owners probably could have been sold to them on their 360 or PS3, so most sales are cannibal sales. This is why the WiiU early launch was important. When the other next gen launch, there may be financial motivation for 3rd parties to put games on Wii U... at least if it's a game good enough to compete with Nintendo's games.
The 3DS is a whole different animal. A user base pushing 30 million and over 80% market share of the handheld space. If you want to sell a game on handheld, it's the only system you need to put your game on.
