Normally, you don't hear about a large team working on a game being removed and replace, but it seems like that just happened. New people are now working on Rainbow Six: Patriots according to Game Informer
The official word is that creative director David Sears has been replaced by Jean-Sebastien Decant. Now, that's the only thing that Ubisoft has confirmed.
Game Informer has three others being removed and replaced as well, all of of whom they interviewed for their cover story
a while ago. If so, this could mean the game's going into an entirely new direction.
2013 was their target year so it would seem they want to change it up about half way through their development. We''ll have to see if Ubisoft comes back with more details on if the other team members were removed and if so, what the reason was and if 2013 still holds true for the project.