A franchise that typically sells 4-5m lifetime getting 4-5m first week?
That really doesn't seem likely. I doubt Sony will even ship enough to sell that much first week even if the demand were there.
Also I think it ll reach a bigger fanbase this time.
They changed the formula abit, reach a broader audience.
"Marty Sliva of IGN said that although the original trilogy are three of the most influential action games of the past fifteen years, he was never able to connect with the series, mainly because of Kratos. The developing relationship between Kratos and his son and the more intimate experience of the new installment, based on the E3 2016 demo, has changed Sliva's attitude and made him care for the series" - wiki
"Peter Brown of GameSpot said that changing the camera was a "smart move" and a change he was hoping for; "it's super impressive." He said the intimate moment between Kratos and his son killing the deer "inspired emotion from me," something that previous installments did not do for him." - wiki
"Alexa Ray Corriea, also of GameSpot, is also glad there is no fixed camera and that players can explore the world." - wiki
They are not alone.
This is going to be a bigger God of War, than you usually see, imo.