ソース:Rumour – Killzone sequel in production, teaser script leaked | VG247

“My sons and my daughters, today we take the first step toward our imperial future. 
“For years, this once-great nation has stagnated in the shadow of its enemies. Governed by scoundrels who flaunted the ideals established by my father, these traitors… these enemies of our race have diluted and exploited the triad of Duty, Obedience, and Loyalty. 
“This regime, this corrupt regime, has been dissolved. In its place does rise an era of stability and strength. A time of opportunity born from a promise that we shall return our people to their proper sphere of dominance.”
となっていて、実際に続編を開発しているならおそらくKillzone 4になると思われます。

ただ、これが実際にトレイラーで流れるのかどうか不明ですし、その続編の対応機種が何であるかについては明かされていないとのことです。とはいえPS3かPS Vitaのどちらかであることは間違いないでしょう。