i think paper money wont disappear. because it is the trade mark of the country we live in. but in my opinion i think it is possible because of the growing technology. and it is much safer not to bring paper money because of the criminals. using encrypted money is much easier and safer.
It will not really disappear it will just cope up with the fast improving technology of our world. As you said, the currency in the future will be more faster and safer than today's. I do not know if I will be just imagining this or Bitcoin will be just the same even after a long time.