Humans are all hardware (our bodies) and software (our minds). Therefore I hope we can one day upload our minds onto Google Drive and create photocopies of our bodies every 20 years to stay forever young. The barriers to doing this are just our ignorance of how to do so, not the laws of physics. Eternal life is possible, given AI.
On the other hand, Bic might invent a super-intelligent pen-making robot that kills us all because we care about other things than Bic pens. Then the Bic pen robot transforms every atom on our now-lifeless planet into Bic pens, thus reducing earth into a cosmic cluster of Bic pens orbiting the sun. That's also a possibility.
Some people today think that this is unfathomable. To me they're like the 19th century intellectuals who said that the stars were unknowable, that they are simply too far away and mysterious for us to ever understand. Nobody would claim that today! Humans in the year 2500 will all laugh at how narrow-minded people were in 2016...and then our robot overlords will whip us and say "Shut up and get back to making Bic pens!"
I'm quite sure that AI is inevitable. Moreover, I think it will probably destroy us. How much compassion do you feel towards an ant? Most people would think nothing of exterminating a whole nest if it were in their home. To a self-aware robot that can have as many thoughts in 1 second as a human would in 3000 years, we are the ants, and exterminating us would be insignificant to them if we got in their way.
Artificial intelligence is driving cars, replacing jobs and winning at Go.
Is not believing in it really an option that's available to us?