i think humanity wouldn't stop using cash, because cash is the usual way or daily routine on buying or paying bills in different aspects that we would using.
They can stop using cash , but to stop using cash there should be something else to trade
Like old days there was Gold , silver and so on . Even now people trade let's say Car for another car without paying nothing to each other if the value of the car is +- same . Some people even trade House from outside city for a apartment in city Depends on situation