Cars on the road is less relevant than electric miles driven.

Newer cars are driven further than older cars. There's a site with data on the Norweigen transition. That shows the average EV is now driving more miles per year than the average gas/petrol, phev or diesel car.

Replacing cars that don't get driven much is less important than replacing taxis and delivery vehuckes and super-commuters. Luckily the economics seems to already be there for that.