EDIT: sorry sent too early

...what changes is the "residual advantage". Until some time ago we assumed machines would only replace people in simple tasks (e.g. mill). Than only repetitive, "mechanic" tasks (i.e. assembly line). Now we realize they can replace in tasks which require some intelligence (i.e. self driving cars) but still assume they won't replace us in some "smarter" jobs. It looks to me like each step is just incremental, I don't see the "tipping" point.