The steam engine replaced a lot of jobs. Tractors replaced a lot of jobs. Calculators replaced a lot of jobs. Computer used to be a job description before it was a personal device. There will be new jobs.
It's not "a lot of jobs", it's "all jobs".
WWI: -20 000 000 extra mouths to feed
WWII: -80 000 000 extra mouths to feed
WWIII: you extrapolate