Sony has declined to comment on rumours that Killzone 3 is "deep in development" and will be released next year.
This is in response to Official PlayStation Magazine's "The Secret Games of 2010" article (via Destructoid), which claimed readers could "pencil in" Killzone 3 as well as Resistance 3 and a Call of Duty: World at War sequel.
Killzone 2 launched in February this year and earned 9/10 here on Eurogamer.
Resistance 2 was of similar calibre, and appeared a few months earlier that Killzone 2, in the autumn of 2008. Insomniac has just finished work on Ratchet & Clank: A Crack in Time, which Ellie is reviewing as I type.
Activision rotates Call of Duty duties between Treyarch and Infinity Ward. The latter will deliver Modern Warfare 2, so Treyarch presumably has something in the can for next autumn.