Paper money is not going to last for more than 3-4 decades.Most of the paper money is going to be demonetized.I think that instead e-money is gonna be popular.Nevertheless paper money is a drag.
Why carry liquid cash,when u can easily do transaction over mobile,? Well I don't think so. Yeah if we're talking about convenience then I have to agree with you that electronic or digital money would be a lot easier than having physical paper money in your pocket. But that requires technology that is not easily accessible to some parts of the world. 40 years from now, you may be right, most people will probably be using digital money but definitely paper money won't be demonetized and will still be used