I can see AI designing more efficiently. That reduces manpower in the design and engineering phase. Maybe using fewer parts or more complex better designed parts.
Fewer parts means fewer jobs. But the real impact is likely to be more versatile robots that can do more complex jobs with less human intervention.
We already have factories run by a small number of humans. Can robots load and unload trucks? Pick and pack orders? Spot mistakes and fix them before shipping? Deal with an empty parts bin or a damaged part?
Maybe fewer humans will be needed but robots that can replace all those functions will take a while.