Despite the ubiquity of mobile payments, a top executive at Venmo says the world is still a few generations away from abandoning cash altogether.

"It's a matter of time — but it's going to be a long time, not a next year kind of thing," said Michael Vaughan, the chief operating officer of Venmo, at the Wharton Global Forum in New York on Friday. "It's still decades, and decades, and decades. It's going to take our lifetime and our kids' lifetime before you start to see this work itself out."

Venmo, owned by PayPal, is one of the world's leading mobile payment services. In the first quarter, the company processed roughly $12 billion in total payment volume in the U.S., which Vaughan said marked roughly 80 percent growth year over year.

Despite domestic growth, the U.S. is in the middle of the pack and "just starting to scratch the surface" when it comes to mobile payment adoption. Finland and Sweden, as well as parts of Asia, tend to be the leaders, while Latin America and South America are the biggest laggards, Vaughan said.

"It's very much market by market," he said, adding that in some countries, people need cash as protection. "It's the lowest common denominator, until you get the whole thing moving along you're going to have to have that other cash piece."

Venmo's parent company PayPal operates in more than 200 countries around the world and is working to expand its offerings. In May, it announced its biggest acquisition yet -- a deal to buy payments start-up iZettle for $2.2 billion.

Mobile payments have become a battleground for financial institutions as millennials, especially, swap cash for digital.

"Everybody and their brother is getting into it," Vaughan said. "But a rising tide lift all boats as more people get comfortable using their phones to pay."

Zelle, a person-to-person payments system backed by Bank of America, Wells Fargo and dozens of other major U.S. banks, launched last year. Square Cash, the mobile payment app developed by Square, also competes with Venmo and PayPal. Since early 2016, Square Cash app downloads have outpaced Venmo's, according to a Nomura analysis.

"It's pretty ubiquitous now, and general it's a good thing for consumers," Vaughan said.