It’s never going to work too far out of Zone 1. Maybe halfway into Zone 2, but no further.
Londoners don’t live and work in zone 1 the way the Parisiens do in their equivalent central zone. We commute into the centre to work, and back out to go home. There’s not enough sideways/radial movement to negate the in/out central zone flow. All any major extension outside zone 1 would achieve would be to saturate the central docks even earlier each day.
Jenny Jones is just making a bit of pointless noise to remind us all that she still exists. Apart from Val Shawcross and Caroline Pidgeon can you name any other members of the GLA Transport Comittee? No, neither can I.