I don't think coinbase/bitcoin will replace anything. At best they might get 1% of that market, but they will never be real competition. Besides the technical issues where cryptocurrency cannot keep up with the same demands credit and banks can. Coinbase sits on a razor blade of questionable ethical practices. Reddit and other cryptocurrency forums always have a handful of people asking for help dealing with exchanges(say exchanges because not just coinbase does this) that either fail to transfer funds or funds just go missing over night. The regular response from people is "it is crypto money what you expect?". Saying it is the normal for money to go missing with no recourse just demonstrate the lack of control and power a end user has in this anarchy financial system.