In fact, widespread adoption will take as long as eight years "at best," Dekkers Davidson, the head of mobile commerce for Barclaycard US, said Thursday.

Davidson told an audience at the here that it would be five to eight years before even a quarter of Americans are using mobile wallet applications. He noted that it took eight years to reach that level of adoption in Japan.

Davidson and other mobile commerce experts on a conference panel said that part of blame for the slow adoption lies with consumers, many of whom in the U.S. are wedded to credit cards. Making the transition to smartphones that are NFC-ready for making payments at an NFC-ready terminal or other technology is simply not a high priority, they said.

"No consumers are really asking for [mobile commerce]," said another panel member, Ryan Hughes, chief marketing officer for ISIS. ISIS is a partnership of three wireless carriers -- AT&T, Verizon Wireless and T-Mobile USA -- now deploying NFC payment terminals and related technology for use with NFC phones in Austin and Salt Lake City.

Davidson said his prediction might change if big mobile commerce players such as Google or ISIS -- or a new Merchant Customer Exchange (MCX) of major national retailers -- have a big impact. Even so, "I don't see a [mobile commerce] winner taking all for a really long time," he said.