I assume it would be a similar situation as arkham knight. They have all the tools etc done to quickly make another gears or just upgrade the renderer and replace assets.
Bear in mind, if their target is 1080p60, I wouldn't bet on UE4's renderer on Xbox one.
I thought Fable Legends was UE4 and if we assume the next gears is UE4 this could be an useful learning exercise helping tool development?