God of War Saga Collection is reportedly in the works for August, according to a Siliconera source. The site's insider doesn't give any details beyond the name, but since there's already a God of War Collection with the first two games, we could speculate that Sony will add God of War 3, and perhaps the God of War Origins Collection (which contains HD versions of Ready At Dawn's PSP games).
God of War: Ascension, the next installment in the series with a multiplayer focus, will be released on March 12, 2013