The number of merchants accepting Visa and other payments cards worldwide may double over the next five years because of the proliferation of mobile commerce applications that target once hard to reach businessesBill Gajda, global head of strategic partnerships for Visa, told the UBS Global Technology Conference in San Francisco this week that "traditionally, and over the last five years, [there have been] above 36 to 38 million places [where] you can use your Visa card.""According to every study I've seen, that number of nodes, places you can use your Visa card in a real-world environment, is going to double in the next five years, solely because of the expansion of mobile point of sale."So, if you think about 38 million going to 76 million-plus, with low cost mobile-centric point of sale devices, clearly that's transformational for our network and the utility of that old mag stripe or chip and pin card."Gajda took an optimistic view of the opportunities for Visa."We're already seeing in markets like Australia, Hong Kong, Singapore, Western Europe, Canada the acceleration of NFC, and, again, I think what KitKat [an application for Android smart phones] has done with host-card emulation is a game changer."I would say that with KitKat Android 4.4 host-card emulation we're going to see, I think, a transformation in NFC… [with] new options for access to virtual, secure elements opening up [these] devices."