November has become a traditional month for system launches (GameCube, Wii, DS are the Nintendo systems that launched in North America then), so that is the most likely time. AC3, if it is a Wii U game, would not be a late port since it would only be like 2 weeks later.
I know November is the most likely time they will launch. But I am hoping Nintendo is watching Apple and their own 3DS launch and thinking about launching at a different time. I know Nintendo thinks the 3DS launch wasn't its best...but I think that is because the games for a good launch weren't there. However, it did get the system out to iron out the wrinkles for a whole year before the Vita was launched which to me has put Nintendo in a big lead.
Apple has also demonstrated that if your hardware is desired you don't have to release it during a holiday season. The ipad3 is rumored to be launching in March or April. This is nowhere near a spending holiday, but people will buy it in droves.
To me a September launch or even an August launch gives first day buyers a chance to jump in and buy the launch games. Gives Nintendo a chance to have 2 games a launch with another 3rd game as the November release.
Also gives a launch window that ends at peak buying season instead of a launch window that ends at the worst buying season. This would seem beneficial for 3rd party developers. As gamers could buy a new system and one or two games. Then come back for second helping in November when they have more money...and more games are available.
I also like the idea of Nintendo making a Wii U play like game that can be bundled with a second Wii U tablet in November which has 10-12 fun multiplayer games. This would allow developers to assume that most house holds will have 2 Wii U tablets.
Yes, November is the likely launch of the Wii U...but my opinion it isn't the best. Nintendo should launch sooner than later, because honestly, they need the time on the market before the competition hits.