There is a basic question here:  Why would AI kills us?  What is its motivation?

The answer is none exists.  To start, AI isnt human which means while we could probably teach it to think, emotions are most likely out of its realm.  Hence, being threatened is not part of its make.  Nor is ego.  Think of all the reasons man kills and you will see it is all tied to emotion.

On top of that, scarcity, at least at the basic level, will vanish.  AI does not need to destroy humans because AI is already abundant.  What is is lacking?  Why would it need to fill a void that doesnt exist?  Again, sans an ego, where is the emotional motivation to feel inferior causing it to lash out.

Finally, AI is not going to be separate from humans.  We will all be one.  As intelligence grows, so does human knowledge.  At present, the device is separate from us but in the future the connection to all the world's knowledge will be in each of us.  AI will not be smarter than us since AI is us.