Panelist Stefan Happ, a senior vice president at American Express, added that merchants need to be onboard as much as the consumer.

And Malcolm Nunes, senior manager of financial services at retailer Home Depot, said digital wallets have to be more than just a payment channel.

When I can have my Passport, my driver's license, and other documents in my digital wallet, then the utility will increase," he said. "There needs to be more non-payment factors involved."

Nunes shared an intriguing fact from his company's involvement with PayPal. Consumers can use PayPal to make purchases in multiple ways, by keying in their mobile phone number, showing an app or swiping a plastic card.

"We had not anticipated this, but what consumers prefer is the convenience of paying with a phone number. They don't have to pull out anything," he said.

And, Nunes said, mobile presents an opportunity to take costs out of the payments system.

"Interchange is our number three expense, after real estate and human resources," he said.

Dodd Roberts, a senior executive with Merchant Customer Exchange, a new payment channel championed by WalMart and others, said in his view, there is plenty of room to slice costs from the payments processing system, much of which was created 40-plus years ago when credit cards were just taking hold and merchants actually used an imprinter to create paper copies of transactions.

Roberts also stressed that a key issue with digital wallets is who owns the transaction data.

"We believe the merchant's data is the merchant's data, and the bank's data is the bank's data," he said. "No third party should monetize that data."

Later in an interview with Credit Union Times, Roberts disputed rumors that MCX was seeking to disintermediate Visa and Mastercard from payments.

"We have had talks with them," he said. "We are open to working with all the payments networks."

As for why American Express had staked out turf in the emerging digital wallets space, Happ said during the panel discussion, "We want to democratize our base."

He elaborated that American Express had a reputation as serving older and white customers, but with its involvement in Serve and Bluebird, the company hoped to broaden its reach.

"We can do this because the mobile efficiencies are so strong," Happ said.

He added that the purpose of a digital wallet is unclear.

"The problem to be solved is clear if it is the consumer without a bank account," Happ said. "An electronic wallet can solve that, and do it without an enormous branch network that no one wants or needs. But I have yet to see any other use for a wallet."