It's quite simple really. People are excited for new hardware. They will buy that hardware reguardless of the quality of the exclusives that it has. The Ps4 will likely be sold out throughout the holiday, until February when Infamous hopefully becomes an actual system seller (instead of just a quality game like Infamous/2).
Driveclub and Watchdogs will keep the momentum high when they launch. It'll work the same way on Xbone, but the reason I'm specifying Ps4 is because it'll have more-so sustained sales with the delayed exclusive Driveclub, especially in Europe where racing games are huge. Sony will need to actually advertise the game though because it isn't very well known when compared to the likes of Shadow Fall and even Knack.
Bascially, Ps4 will be fine and sell out throughout the months. These delays will help reduce the possible "WiiU" drought effect. Also Xbone will sustain a lesser amount because of Watchdogs, but will still benefit.