Borderlands 2 has just lost some competition this early Fall as Far Cry 3 will be delayed until November 30th in Europe and to December 4th in the US. Thus far, Ubisoft has not commented on the cause of the delay.
With such a late release, Far Cry 3 could be buried underneath everything else that is releasing the October/November time frame. A September release was probably Far Cry 3's best, and most optimistic, launch window. This isn't to say that it won't do well, but I don't see it doing as well as it could.
Just please don't delay it to February. No more February releases, for the love of God.