The CryEngine 3. If we assume that this series is now a prequel to Prime (allegedly) then I'd love them to make a homeage to Transformers on PS2 which has you go around the world to find artifacts. This would bring highlight the greatness of the Cryengine 3. If you've seen any of the Crysis games you can see how the environments look great as do the models. Also I'm sure that the levels can still be quite big. Plus this will keep the game fresh.