As far as I know no engine out there is able to do what the creation engine can, and that is having world spaces with tons of persistent dynamic objects. If they would switch to another engine they would loose one of their core elements of the game, the possibility to take all the junk that is laying around in the world or to add things literally wherever the player wants. But this feature comes with the price that the world spaces have to be comparted in cells which are separate by loading screens. This can be minimized with streaming and dynamic data transfers but this has its limits too, even more so on resources constraint systems like consoles.