It sounds like Pikmin 4's core development is perhaps nearly completed, or maybe just needs time to be polished, but due to the upcoming launch of NX early next year, Nintendo had to prioritize development staff to other projects deemed more important. If this were a flagship IP, then it would have likely been a different story. We saw how games in prototype development, such as Zelda: A Link Between World's, had just finished its prototype yet could not enter production because Nintendo needed the 3-man team to be assigned to next-gen Wii U launch software (Nintendoland and New Super Mario Bros U). I don't really see what the point of wasting resources on releasing a Wii U version of Pikmin 4 if it takes away it being an NX launch title or a post-launch release in order to help provide much needed software momentum in 2017.