They still don't know it yet, trust me on this one. They want to place the game on a date that will benefit them, but there are still too many unconfirmed schedules, including their own recent Assassin's Creed Unity delay and now both Unity and Rogue are comming the same week. They also want to avoid Call of Duty release date, and the rumored GTA remaster.

This makes a lot of sense.

But then, they missed thier golden opportunity. The original launch alongside  MK8 ended up being the best time.

True, but saddly it was the right financial decision, their teams were having trouble closing all the bugs and problems of the versions of the game, so when they looked at the dissapointing sales of ACIV for WiiU, that was launched alongside the other versions, they chose to split the Wii U development team (who are very good at the technical stuff) and let them work on the other versions, because those sales were coming but only if they took advantage of the hype around the game.

It is kind of interesting that after releasing the other versions and knowing that they are going to sell very low numbers, they allow them to go back and keep working on the Wii U edition at all. You can say that the developers are salvaging their efforts, but I don't like that people dismiss them just because their parent company took a business decision, they are still making an impressive effort and I would love that those who have not yet played the game on another console give a chance to the Wii U edition.