His total assets were quickly converted to New Yen, a fat sheaf of the old paper currency that circulated endlessly through the closed circuit of the world's black markets like the seashells of the Trobriand islanders. It was difficult to transact legitimate business with cash in the Sprawl; in Japan, it was already illegal.
I am fairly convinced that using cash will slowly be labeled as a "criminal" activity and gradually shamed into non-use by regular people.