Money is only an agreement from the lender that he is liable to pay the borrower the certain amount of goods or services equivalent in the foreseeable future.If we look at the history of money, in the initial days, there was no concept of money and only one type of good was exchanged for another type. Through the evolution of time, the concept of bond or agreement to pay the borrower in future came forward.This idea changed the way we exchange our services for another. Instead of directly being paid with equivalent amount of another substitute we were given paper notes which became the medium of exchange.So going in this way, the future of paper money isn't very illustrious, cause it is very susceptible to damage by natural and man-made(e.g robbery or fake notes etc) causes. So I think the future money will be digital, where the concept of bearing liabilities would be the main theme without any real exchange of material stuffs of any kind.