Based on this picture above, it is definitely saying God of War 4. The word "Vengeance" was a big part of God of War 3. It also helps that god of war 3 ended with little bit of a cliff hanger, showing blood tracks to the edge of the cliff and no Kratos body to be seen.
In that video Kratos seems to have crawled after stabbing himself with the blade from Zeus but we are still not sure what happened there but we we will soon find out.
But going back to the picture "Will Vengeance bring Redemption?" Kratos lost it all. His Family, His life, and His soul at some point until he killed all the gods (including his father Zeus).
Idea Number 1: The Story might go towards fixing what Kratos has caused because if you guys seen from the video, it's a mess! The environment is just so terrible! So that might have to be something to fix.
Idea Number 2: Maybe he finds out a way to bring back the fallen gods! Reborn some or some crap like that you know.
Idea Number 3: Maybe he has some sorta goal and he is going to give it all to do that. No matter how bloody it is he'll complete that goal so I don't really see the first two goals to work unless he reborn the other gods to be slaves for him. He only cares about himself mostly but he is still human.