Ai

yeap i think it was the terminator with arnold that took care of that...
I think that the ai will not be able to take over not because they won't be smart enough but on the contrary that they will be smart enough to realize they have too much to loose without us. as a species we have eveolved without ai for years and we did ok... ai cannot say the same, plus they need us to pursue their development and third even if they reach total indepandance a simple em wave would turn all that back to scrap metal. Fourth and most important they'll aslo realize they have too much to gain in symbiosys with us for we need each other and that life would not be the same witout the other one (kinda like a mariage)