Get rid of all the cash?
Probably sometime, but this is still a long way ... of course, this is not only our (user) goal but also (probably even much more) governments, because cash still remains the most difficult way payment to track down...
However I think needs very long time and saying that I do not think about years but rather about decades ...
cash may be difficult to replace completely with crypto, it takes a variety of tools if you want all trades to use crypto. the best possibility is that cash is still used and crypto currencies can also be used. all currencies are used according to location and circumstances.