Has GeOW2 even been announced yet?
GeOW2 wouldnt outsell GTAIV and GTA:SA wasnt the best GTA ever but it was still good hopefully GTAIV can revitilise the series to what it used to be.
Halo3 might outsell GTAIV but that would probably be a close call i think they are both very hyped and massive franchise.
End of 2014 Hardware Predictions (03/03/14)
PlayStation 4: 12-15million
Xbox One: 7-10 million
Wii U: 8-9 million (Changed 01/04/2014 from 7-9 --> 8-9 million)