Many expected the God of War 4 (or the next God of War, however you want to call it) to be announced at the beginning of December at PlayStation Experience. It kind of happened, but it was just a mention in passing of which Sony Santa Monica tried very hard to erase any trace.
Before I proceed, let me put a disclaimer right here: this is full-blown speculation. We have no insider knowledge and this is just an analysis and opinion on what has been publicly disclosed. I could definitely be wrong, so take it with a grain of salt.
Today Shannon Studstill, Studio Head at Sony Santa Monica, mentioned that the developer is going to host a 10th anniversary celebration for God of War in March, and expects to play an important role in a still unannounced PlayStation Experience.