I think it is entirely possible that we will drop "cash" as we think of it today.  You touched on an important point;  a lot of people have already stopped using cash, even before crypto came along.  I know that personally, when I receive cash it is a bit of a nuisance in the sense that I am most likely going to have to make a trip to the bank in order to use it.  When a digital form of cash comes along that becomes easier to use than traditional cash, logic dictates that it will render traditional cash obsolete.