The rote, unskilled work in auto assembly was easily automated (apply a spot weld here, insert a part there) but a lot of the skilled work was as well. The precision parts in automobiles used to be made by hand by machinists. This was highly skilled work, and it's now almost entirely been replaced by CNC. Machinists today, to the extent they still exist, are much more like programmers. They are still used for small and one-off jobs, but mass production of machined parts is programmed directly from the designs now, so you don't need a machinist in the picture at all for that. No amount of keeping up with innovation would have helped there.

If those people were let go (or retrained) continuously as they became redundant, instead of being employed in a unsustainable behemoth which then collapses all at once, they are much better positioned to re-qualify and re-join the workforce (maybe in the same, maybe in a different company) in a higher-skilled position. This could happen multiple times over a career.