Do you think that Harrison is being guided by another villain more powerful like Bane and Talia in The Dark Knight Rises?
Maybe there will be a scene at the end of the credits that goes something like this:
SCENE: Harrison enters a dim room, dusting himself off. A figure stands in the darkness.
Harrison: I have done as you asked, and have exacted my vengeance. Now it is time.
Figure: There is a proverb that says: 'Revenge is a dish that is best served cold'... It is very cold... in space.
The figure emerges from the shadows, and we see it is .... Khhaaaaan!