If Uncharted 4 can go on to sell around 12 million + copies, then I see no reason why God of War can't be the top seller in it's franchise, especially in an age where PS exclusives are selling extremely well.
Uncharted 4 did 8.7m on its first 9 months, so GoW doing 5m on its first 3, and outside of holidays, is not something easy or guaranteed. But I'm pretty confident it will too.
Bet with Teeqoz for 2 weeks of avatar and sig control that Super Mario Odyssey would ship more than 7m on its first 2 months. The game shipped 9.07m, so I won