Banking system is upgrading itself automatically from time to time for the demand, security needs and vulnerabilities. All of us know about it very well. Bitcoin is a paperless currency. We do need banks for bitcoins too. Paper currency may not disappear even though bitcoin reaches moon. We would soon see dual currency operating banks.
Only about 3% of currencies are paper and coins. All the rest is nothing but bits in a computer. Paper currency is already disappearing. (If it was alive, it would be on the endangered species list.)