For me I do not think that there is coming a big surprise for the paper money in the world because paper money will always be the number one paying method for the most people so i do not think you should worry about that.
Paper money is very hard to determine what is going to be its future. But still that is not a problem because people tend to use paper money.
And I don't think paper money is going to be out of the league when bitcoin gets popular at all.
It will exist forever in my opinion because that is the simplest means to use in all kind and forms of transactions, you can easily use it anywhere with the need of power and internet.