If we assume, that an AI emerges that is thousands of times more intelligent than humans, then it would take over control of the world from us humans, I agree. But is it necessary a bad thing ? Just look around how dumb our humanity is destroying the world, driving most species out of existence including the homo sapiens species. It would be very refreshing if more intelligent AI would take over and stop the idiocracy that is currently ongoing under our oh-so-great leadership.
Would such AI really enslave and exterminate us ?
When humanity was at a more primitive, lower level of intelligence, we had slavery, genocide. Most of us have risen in intelligence to the level so that we do not go around willingly exterminating other species. If the AI is thousands of times more intelligent than us, then they would value life and would help preserve it. Sure, we would lose control, they may limit our freedom, e.g. not allowing us to continue our wanton ecological destruction.
I, for one, would welcome such overlords!