maybe there will be some AI that turn evil
That's the critical mistake. AIs don't turn evil. If they could, we would have FAI half-solved.
AIs deviate from their intended programming, in ways that are dangerous for humans. And it's not thousands of years away, it's away just as much as a self-driving car crashing into a group of people to avoid a dog crossing the street.
Even your clarification seems too anthromorphic to me.
AIs don't turn evil, but I don't think they deviate from their programming either. Their programming deviates from their programmers values. (Or, another possibility, their programmer's values deviate from humanity's values).
http://fusion.net/story/54583/the-case-against-killer-robots-from-a-guy-actually-building-ai/
(An earlier version of this article was titled 'Andrew Ng disses UFAI concerns" which is the phrasing many of the commenters are responding to).