I think 3D World is going to sell fairly well to current Wii U owners. The problem is there aren't that many of them. Still, I would be surprised if it doesn't pull in 300,000, 400,000 in sales. If it is anything like you fear, Nintendo might as well pack it up and never release another game on that system. If Mario can't sell, forget it. Maybe push Smash and Kart out the door if they're close to finished, but otherwise? Tap out.
But again, I don't think that's going to be the case. 3DW will do at least 300K. That's my lowest possible acceptable number.