"I think cash will live on longer than anything because the central banks want to issue cash and control the amounts," Ersek said in an exclusive interview with TheStreet. "They understand what the value of the economy is and that is why you issue money."
That's not to say the growth in mobile payments shouldn't be taken seriously. The numbers don't lie. Total mobile payments transactions are expected to reach $8.7 billion this year and grow to $27 billion in 2016, according to data from eMarketer.
"[The increase] shows how the customer's behaviors are changing," Ersek said. "Things are all done by mobile and people want to [add payments to the function of a mobile device]."
Ersek likes the payment platforms from Apple (AAPL) - Get Apple Inc. (AAPL) Report , Alphabet's (GOOGL) - Get Alphabet Inc. Class A Report Google business and Facebook (FB) - Get Facebook, Inc. Class A Report .
"They want to offer the customer a new service, besides only communicating with your phone," he said. "They want to provide consumers with real services and real services only happen if money moves."
Recognizing that the future of the industry lies on the mobile and social space, Denver, Colo.-based Western Union launched its own version of Venmo, called WU Connect, in late October.
"The customers were telling us that they would like to have more access points to Western Union and also that they wanted to connect with their loved ones globally," he said.
But Ersek doesn't think he's late to the game, since Venmo has been around for four years.
"What Venmo isn't offering yet -- and doesn't have the capability yet -- is cross border transactions," he said. "It's easy to send money from Denver to Los Angeles with Venmo, but it's not easy to send money from Denver to Mumbai," because of regulatory and compliance issues.
Ersek said he's focused on international transfers, thanks to the company's 500,000 agents in some 200 countries worldwide.