User blog comment:Deathmanstratos/Some Call of Duty: Advanced Warfare singleplayer background information revealed/@comment-1187559-20140508183057

To be honest I think it's more likely that "a brand new engine" will mean exactly the same as Ghosts. It'll just be a heavily modified version of the current engine. While Sledge has been given a good amount of time to work on this, I'm not really willing to hold my breath it's something completely new like the transition from Gamebryo > Creation.