FORTUNE — What kind of technology will propel us toward a cashless, mobile payment-driven world? For a few of the companies leading the way, the answer is as uncertain as ever.

Speaking on panel about mobile payments during Fortune’s Brainstorm Tech conference in Aspen, Colorado, some of the players in that market denounced near field communication — the technology that some have heralded as the driver of the cashless revolution. EBay (EBAY), which owns PayPal, has already famously shunned the technology, which allows mobile phones to make transactions by tapping on them. (At a Fortune event earlier this year, CEO John Donahoe said NFC stands for “not for commerce.”)

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While panelists acknowledged the role that the buzzy technology would have, none thought it would be a cornerstone for the market. “It’s part of the solution,” said Ron Hirson, co-founder and president of Boku, a payment company that deals directly with carriers. “It’s not a global standard for payments.” Dawn Lepore, a former eBay employee and now CEO of Internet loan service Prosper, says the market will be much more segmented. “I don’t think it’s winner take all,” she said. “There will be multiple successes.”

Still, faith in NFC has gotten a boast recently, with rumors that Apple’s (AAPL) next iPhone will include that technology. Hirson conceded that if the tech giant gets into the game — which he thinks won’t be for years — all of the players have a fierce competitor. “Apple is notorious for waiting to do something, then doing it right.”

But in the meantime, companies like Square continue to tackle the market for small merchants. They just got a little more competition.

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The financial technology company NCR — currently most well-known for manufacturing ATMs — today launched NCR Silver, which turns an iPad into a point-of-sales device. The company is launching for now only in the United States, but plans to be in China, Brazil and the United Kingdom next year. But CEO Bill Nuti is not arrogant about jumping into a space that is rife with moving parts and has no set standard. “We’re not overconfident,” he said. “We’re very humble.”

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