I think AC Unity will flop. It is coming out on the same day as Halo Master Chief Collection. Majority of Xbox One owners will be spending time in multiplayer on that game (I know I am). Last gen isn't going to help them out in sales, since they can't play it, and they got AC Rogue coming out the same day. That pretty much leaves the PS4 (Pissing off PS4 owners ain't going to help) and PC with that week open. Dragon Age, Project Cars, Far Cry 4, WWE 2K15, LittleBigPlanet 3, and GTA V all coming out the week after leaving no breathing room.
Ubisoft title + 2 weeks out from Black Friday + avalanche of titles in November = crazy sale on Black Friday.