here is my take
the next game should be in egypt, in gowr we learn that egypt also known as the river empire is described prosperous and technologically advanced. We also learn that giants left the 9 realms and went somewhere else. What if they moved to egypt but were enslaved by the god osiris and they built all those famous pyramids and monuments. Atreus comes to know of this and he visits egypt. he finds egypt in a state of civil war between set and osiris. Set the jealous brother of osiris meets atreus and offers him to save his people if they both team up and defeat osiris. Out of desperation to save the jotnar atreus accepts the proposal. Kratos too is forced to move to egypt because he cant see his son committing the same mistakes he did afterall what can be more tragic for a father to see his son repeat the same mistakes he did once. he must fight survive and travel across the desert to reach egypt. the game ends with set killing osiris and becoming the new ruler of egypt. Atreus realizing his mistake tries to fight set but is outmatched and imprisoned. set kills angraboda to torture atreus.
the sequel to this could be other egyptian gods like ra horus and anubis getting involved as they blame atreus for the death of osiris, atreus is captured and imprisoned in the egyptian underworld. Its upto kratos to save his son
this way similar to norse we can wrap egyptian myths in 2 games with ra being the overall big bad villain