Would this actually ever make any sense? Not counting totalled vehicles. There really isn't so much profit in new cars price that it pays for used car fully. Unless that used car is really heavily used. Which then leads to questions of how much lifetime left the parts have.
They could lobby and get another cash for clunkers sort of arrangement from the federal government to incentivize dealers turning over leases rather than having them on the lot, and having the cost of getting back these cars publicly subsidized by the government. The run for used car supply right now is entirely due to new car supply being so strained. Pushing that demand back to new cars rather than used cars puts the profits back into the automakers rather than dealerships, and guess who swings with more weight in Washington. Not Joe Shmoe Chevrolet from Anytown USA.
How long longest leases are really 7 years? Is there relevant usable parts left in those vehicles? On other hand with shorter leases like 2, 3 or 5 years the cars are still perfectly functional and scrapping them would be huge waste just from environmental point alone.
Simplest thing might be just to pay some part of laid-off workers compensantion.