In this day and age, robots don't have the ability to threaten humans. While we can program them to do remarkable things, they are not self-sufficient and can't be considered threats to humans. No matter how intelligent our current robots are, we still have the ability to shut them down or destroy them as need be.
Currently, the artificial intelligence technology created by Google and other companies is far too rudimentary to achieve the kind of ‘self-aware robot’ catastrophe that movies such as Terminator have popularised. It is also worth noting that the creators of the AI intend their kill switch to function as a ‘forget switch’ – similar to that of a factory reset and they are not concerned about their technology hurting anyone.
While robots could certainly threaten the lives or livelihoods of individual humans, I do not believe that they pose an existential threat to humans. The subjective nature of human reason will always be perplexing to robots who will always, at their very essence, still be binary beings, seeing that world in black and white. as such, humans will always be too perplexing and intriguing for any AI being to desire to eradicate independently of human instruction.
Because AI learns from its past experience and adjusts its future actions accordingly, a big part of the kill switch is the ability for the AI machine to not learn how to prevent future interruptions. However, the goal is to not have the kill switch impede an AI machine’s ability to learn. Although there is always a risk involved with new technology, especially with technology that can think for itself, research by the top AI scientists in the world should help create a safer, more advanced robotic world.