That's thinking too small. There are those who believe that the implementation of sentient AI in fact represents the
de facto* end of human life as we know it, whether or not this AI is hostile. This is what is known as a
technological singularity (apologies to those who protest linking to the Wikipedia). A technological singularity is the point in human technological innovation after which humans cannot possibly comprehend further advancements, thus rendering all previous models of human progress irrelevant. This is generally envisioned as the product of the creation of superhuman Artificial Intelligence, the augmentation of existing human intelligence, or (more generally) the emergence of any technology that is inherently incomprehensible to humans.
The possibility of the singularity is certainly forseeable as a consequence of Kurt Gödel's
Incompleteness Theorem, which states (and I'm oversimplifying terribly) that true but unprovable statements exist in mathematical logic. The technological singularity is depicted as the result of aggressive artificial intelligence in the
Terminator and
Matrix series, but is also present in the seemingly benign augmented intelligences of the
Neon Genesis Evangelion series.
Indeed, while strong Artificial Intelligence certainly represents another step in human technological evolution, it is arguable that it also signals the evolution of human life itself and the end of the dominance of "human life" on Earth as we know it now-- perhaps an end to civilization as we currently define it, but also perhaps the beginning of human extinction. Not that I have a problem with any of this, but then again I'm a cynic with very few human morals or scruples.
* I'm sure I pissed off someone in the "Words/Phrases that you Hate" thread.