I'm betting that there are three big reasons why No More Heroes for the Wii U never happened. Neither No More Heroes 2 or No More Heroes: Heroes Paradise ended up selling as well as the original game, potentially signaling to Grasshopper that interest in the franchise was on the decline. Couple that with the relatively small install base of the Wii U, and Grasshopper's subsequent partnership with mega-money mobile publisher Gung Ho, and you have all the ingredients needed to kill any chance of No More Heroes 3 appearing on Nintendo's latest console.
Still, Suda51 hasn't entirely given up returning to Santa Destroy. In a recent interview with Gamereactor, Suda said "Yeah, No More Heroes 3, I get a lot of requests from fans and I'm very grateful for that, but I'm thinking it may happen within 15 years or so? (laughs). Maybe not through Kickstarter, but GungHo would of course be supportive if that were to happen. I think I have the vision that Travis forgot something, so I really have to have him to go back and get back what he has forgotten. But yeah, I definitely want to make it possible, but I also want to create something new, so maybe within 15 to 25 years (laughs)."