The news first broke in an interview between Barlog and the gaming site Kotaku. In response to a question regarding the long development period of the recent God of War title, Barlog answered: "A big portion of the five years was, we had to start from scratch. We had a core engine but we really redid a lot of stuff," The interviewer then goes onto suggest that the next game will be released in two years time, with Barlog not correcting him or offering a direct comment.
At this current period, it is unlikely that Barlog will have an idea about when the follow-up title will be released, and whether it will come to the PS4 or PS5. However, it has only recently been rumored that the PS5 may be on for a release in 2020, but no concrete details have yet been announced.