I think that cash is something over lived and should not be existing anymore though I am not supporting anything like credit cards neither. Whole fiat currency system simply does not work and should be replaced. The best alternative are cryptocurrencies in my opinion because those with limited supply and proof of work or stake cannot be cheated.
I have made a post about why I think crypto is better that fiat so check it out if you want! https://steemit.com/bitcoin/@mischaro/why-is-cryptocurrency-much-better-than-fiat-currency
will do