The faster the rate of the technological progress, the larger the portion of the labor force that is in this transitional state. Also, when technology eliminates a whole job category there is often a period of education for the jobs that remain. What is lost in much of the contemporary discourse is this ephemeral nature of technological unemployment. Keynes did not condemn 'technical efficiency' but rather posited that it could happen too quickly.
The jobs that remain will be at high demand, and competition too high for everyone to fit in.
As technology advances, the requirements to do a job will be increasingly intellectually higher, and the bast majority aren't cut to deal with that, that's why we are headed towards a point of no return when it comes to permanent unemployment.