One of the frequently used functions of Credit Cards is to provide a guarantee of an uncertain future payment without having to lockup cash in deposit/escrow.
For example: hotel bookings/security deposits, car rental guarantees, AirBnb rentals, Uber taxi.
Bitcoin does not work well for these types of uncertain future payments / guarantees. Even with a Multi-signature wallet payment, when BTC is locked in escrow there is a value/exchange rate uncertainty as well as the need for the user to put funds up in advance. Neither of these features is likely to persuade customers or merchants to use crypto-currency for payment instead of a credit card.
If an ETH smart contract could be developed which could replicate the features and benefits of a credit card pre-authorisation without the limitations of BTC payments that might be a rather compelling Dapp for early mass market adoption.
Let's use this Discussion to see if we can share thoughts about how such a Smart Contract / Dapp might work.