Although we are entering an age where everything has its digital version, I don't see the paper money being obsolete. It is still nice to have physical forms of money. The increasing transaction counts using digital money and online payment has reduced the need to bring cash but there are still things that are better off being paid by paper money.
Of course, the use of paper money will still be practiced as there are situatio or good/services that will require a must to be transacted using paper money. No matter how civilized or advanced that the word may become, paper money will still be needed to make some forms of transaction.
Personally I disagree, payments are becoming more and more digital, just look at bitcoin and electronic currency, the tendency is that cash is disappearing, and in the future theres a big chance that in developed countries cash will no longer exists
Within that trend, it is possible that the bitcoin will be the major global currency gradually. the price will also rise.