mckenndk: It's hard to say if you will get rid of Guards, you will need a person at every station if you do to make sure all the doors are shut and everyone is on safe, even in the uk with their electronic ticketing system you still have guards on trains to make sure you have bought the correct ticket and for safety.
I'm sure I've been on commuter trains going South of London that didn't have guards. The platforms had banks of video monitors showing the doors where the driver could see them.