I think, people who say that believe that we’re close to actually-intelligent AI (or artificial general intelligence, AGI). And when we get there, it’s possible that we might suddenly be able to automate lots of complex tasks, possibly even shove it onto robots and have it take on physical labor and things like that.
It’s the wet dream of capitalists, because they don’t need to employ anyone anymore. And I guess, folks are also afraid that such AI could be used for war.
You don’t experience anything, not even a sense of ‘nothing’.