The future of paper money is looking sad cause paper money is old and doesn't fit in our current era anymore so we have to see when it will be killed.
But i don't think bitcoin will be the one to remove the paper money though it will be something else.
I think the future of paper money is still long enough in the economy because the government is able to control and manipulate the cycle of fiat money in a country. But it is true that it will be changed because of the fast paced happening with technology. I guess the currency will be digital but still the same value and the same name.