A sequel to this is a terrible idea , leave this film alone!
I really loved this film but come on , it had a beginning a middle and an end.Robot was victorious even if he "lost" -Father/Son grew closer , it all ended like it should.
I think adding a sequel will spoil the nice ending of the first film.What will we see in a sequel ? The main character with his now 16/17 year old son (I dont know the real age of the kid but he was already much taller/older in "Dark Skies") prepping the robot for some world championship---That would just be terrible ...
I personally think they should leave the characters where they were at the end of the first film.
It is the sort of story that should be a one shot. I really hope the planned sequel wont happen any time soon...