I have been thinking about this for quite a while now. If Onaga gets destroyed in MKD then who will be the next villian.
My theroy is that when he is destroyed then someone that isn't bad will rise up and become evil and they will have to contain that new evil or maybe an already evil person will hunger for more power.
Like say after Onaga dies then his spirit still lives on and somehow posesses one of the good guys such as Sub-Zero. And he turns on all of his allies and Onaga's spirit gives him uncontrollable powers and his Ice power increases at a rapid rate..........And it continues onn