EDIT: I also believe that the time to actually transfer funds with a credit card in in the area of weeks, not seconds. The merchant has to sit on the transaction for a pretty long time before they actually get money from the CC company.
A merchant is also hindered in that the CC is soft, a customer can dispute and possibly reverse the transaction in the future. It requires that the merchant have a credit relationship with the payment processor. The merchant also pays a significant fee not traditionally passed on to the CC customers, but to all customers.
Customers may prefer the CC, because it provides reversible transactions and hidden fees not directly paid by the CC user. Using the collected fees, the CC company gets to play silly games with points and cash-back programs to attract customers that are paid by all customers of the merchants.
Merchants will be the one to drive adoption, due to the advantage of much lower fees and irreversible transactions, and a merchant can accept payments without establishing credit with a payment processor.