No one can tell this. Even because there can be credit or debit card connected with bitcoin. Everything will depend from the convenience. If the use of bitcoin will be more cheap there has big probabilities that he became the most used. If the credit/debit card will waived their fees for payments in internet or will decrease those in a minimum level I don't think that bitcoin will replace so. It is not so spread like the credit/debit card. Anyhow, bitcoin will remain for sure the preferred currency for their who will want to remain anonymous in doing payments.