[Impossible]

I think this says more about the current state of AAA games rather than Unreal Engine. Batman and Mortal Kombat have years of engine and gameplay work and diverged from vanilla UE3 a long time ago. It's easier for those studios to upgrade their renderer and port to modern consoles than it is to throw out and rewrite years of custom work. Other surviving AAA franchises use in-house publisher engines or long running franchise specific engines.

ARK (http://www.playark.com/) is a solid success, but it's a mid-tier game. Fable Legends, Gears of War 4, Street Fighter V, Lawbreakers, Tekken 7 and a handful of other games can probably be considered AAA. Given where the games business is right now I think most commercial UE4 titles will be mid-tier indie titles from ex-AAA developers, and Epic has tailored their business model and engine to reflect that reality.