It could get delayed ... At this rate I'm not expecting it to release until early December.
Them releasing the 3DS version first makes no sense to keep the WII U version a secret since the damage was already done and it'll be very hard to justify purchasing the WII U and Smash for a $150 premium compared to what's offered on the 3DS.
If anything the better idea it's a better idea that Nintendo announces the game as soon as possible for the WII U to help damage control that Nintendo released Smash Bros on the 3DS first ...