Not sure who’s job it would replace. Right now policing boarding order is done by one person who is responsible for a bunch of other things that are critical for the flight. Even if they want to trim staff, and they do, that isn’t a place they can do it.
That person is responsible for handling the weight and balance for passengers, bags, fuel, and cargo, acting as the interface for the above and below the wing personnel, managing access to the jet bridge and aircraft, securing the aircraft on the ground, and scanning in passengers. Policing boarding order is a very very small part of the job. Even if they find a way to automate the boarding process, you still need an operations agent. Airline management can be questionable but they aren’t that bad.
More likely would be trying to get rid of the CSRs, something some airlines have done. That causes its own problems though.