If I'm not mistaken, Yamanote Line trains still have guards, would the driver just become a second guard or will all on board staff be eventually eliminated?
Putting aside the matter that this is Japan and they still like human operations for some reason (look at that Keikyu video of manually controlled interlockings), starting with the Yamanote Line may be a bit ambitious IMO. Perhaps they could do something with ATACS and a smaller line first?
What would likely occur is a form of “one man” control where the operator is in the front of the train using on board and platform mounted monitors to see and controls the doors, and is only there to operate the train in the event of an anomaly. This is the same as MARTA in Atlanta and TMRT in Taipei.