-Digital books and kindles replaced library books
-Regular mail was replaced by email
-Previously, we took actual photos; now we take digital photos
-Digital music replaced cassettes and CDs.
-We switched to direct deposit from cash or checks.
How often do you actually have cash? It's rare that I do! The next item on this list is money.
Then... Buy Bitcoins.
All the example you give, one replace the other one. But as for the money and digital money of a thing. I did not see where the digital replace the fiat. But, I can see that two of them can exist together because one need another one to grow or to continue to grow. So instead of seeing the case as replacement, just see them staying together and competing in the economy.