Good luck getting a ticket office to advise on 'complex' ticketing!So first you need to make ticket offices redundant by having a ticketing system that is straightforward and usable. Then it's possible to reduce the ticket offices to dealing with complex ticketing queries and smartcard issues, rather than day to day retailing.
All we need to do is continue enabling more and more tickets for e-ticket fulfilment, including Rovers, Day Rangers, PTE products and then you can simply buy online, just as you can in sensible countries such as Czech Republic.
It's far easier to book a longer journey, and get the seat reservations you want, online than at a ticket office.
That said, there will always be a need for staff at some stations, but the staff may be better off being given a different role than sitting inside a ticket office.
I don't think ticket offices can be dispensed with any time soon as there are too many products that are unavailable online; that needs to change first.