The only way this could ever work safely is if you partnered with a credit card company prepared to treat a record in the blockchain as sufficient proof to refuse a chargeback.

Or if you treated credit-card bitcoin purchases as options. On the surface it's not a good idea for someone to accept credit cards for bitcoins, but why can't I use my credit card to purchase BTC at the current rate for, say, April 15 delivery? Of course, now I have to trust the seller to follow through, but that's a tractable problem that can be solved with either reputation-based trust or escrow services.

I like this. Do you know how long one would have to wait for chargebacks to be no longer an option?

At a minimum, chargebacks can occur months later. The chances of a fraudulent chargeback would go down the longer you waited, though the changes of a legitimate "why don't I have my product yet" chargeback would likely go up.

I think it's a pretty solid way of establishing "delivery". But Credit Card company supporting BitCoins, that doesn't sound too probable, since easy availability of BTCs could be a threat to Credit Cards.

Haha!