Sony Computer Entertainment America Santa Monica is currently hiring a senior online programmer to "join the God of War team!" Applicants must have experience "designing and implementing systems and tools to support networking needs (such as in-game communication, client-server, matchmaking, [and] leaderboards)."
That latter part of the ad makes it sound like SCEA Santa Monica's next project will support online multiplayer in some form or another. (SCEA reps had not commented on the matter as of press time.) However, there is no guarantee that the studio's next game will be an entry in the God of War series, although the finale of God of War III did leave open the possibility for a sequel.