I'm not sure how many lost their jobs to the machines at all. At a glance there appear to be about 4 attendants per self-checkout area, which is at least a dozen self-checkout machines at our local Walmart, so they all stay busy enough what with telling the machine I'm old enough to buy beer and such.
Minus the self-checkout machines I could imagine 2 of the 4 clerks running the usual "not enough cashiers" play that stores got famous for, with the other 2 being sent to the back for whatever duties. Possibly they aren't hired at all.
If my questionable observations are accurate, then that means that maybe Walmart is getting more throughput, with everyone ringing themselves up, but maybe they aren't spending a bunch less on labor.
I can't see anybody going back on the self-check machines, though. Not after all that money spent, and the decade that retailers have spent waiting for customers to learn how to do the job themselves, especially the older folks. That was a bitter change to buy, so it's wishful thinking that we're going right back to human checkout only.
Hell, Aldi just installed a couple self checkout machines here. They were the one holding out, too, since an Aldi cashier zooms the groceries through so fast it's tough to justify. Oh, and they're trying to have that one person, with shoppers in front of them, also be the attendant for the self-check machines. I double scanned something by accident and the clerk had to stop their own line to help me by pushing a button from way over there and then back to scanning they went.
Come on, Aldi.