They will have to enable the machines to carry out all transactions. Some may need to be verified by staff.As far as I am aware it is not possible to purchase child, disabled, privilege and certain other reduced ticket types from the self service machines. There is obviously a need for this facility to be retained.
This could lead to better service. At present, people trying to get a Railcard discount loaded onto Oyster are being fobbed off at some stations being told it cannot be done.
When this can be done by machine, the passenger can bring it all up and ask the staff member to approve it. The staff who deny existence of this facility will no longer be able to deny it exists if the passenger has found it themselves.