I look at AI as a continuum or evolution of software to do more for humans.

Today, if you make a phone call and a computer operator picks up, the experience is not as nice as it could be. In 50 years, it may become indistinguishable from talking with a human.

Similarly, a google search may become more intelligent. Facebook is already going this way with Project M.

Calling a cab via uber may result in a software-driven car picking us up. There is no evidence this kind of intelligence will threaten humans. It's just a tool.

Humans are in the business of solving problems, AI helps us solve problems. Killing us is not solving a problem