Bottom line: Starbucks managed to capture a sizable market share and hold on to it over the past few years but as eMarketer highlights, its growth potential is limited due to the fact that it can only be used at Starbucks stores. It was really only a matter of time before a more generalized platform took over due to the simple fact that it can be used in more places.

Apple Pay is now the most popular proximity-based mobile payment service in the US, outpacing longtime category leader Starbucks for the top spot according to eMarketer.

In its last mobile payments forecast in May 2018, eMarketer predicted Starbucks would be the most used mobile payment platform in the US with an estimated 23.4 million users. In reality, Apple Pay grew faster than anticipated as 27.7 million Americans used the app to make a purchase in 2018.

For 2019, eMarketer forecasts 30.3 million Americans will use Apple Pay with Starbucks coming in second with an estimated 25.2 million users. Google Pay is forecasted to finish in a distant third with just 12.1 million users followed by Samsung Pay with 10.8 million users.

eMarketer principal analyst Yory Wurmser said Apple Pay has benefited from the spread of new point-of-sale systems compatible with the NFC signals used by Apple's payment platform. This should also help Google Pay and Samsung Pay, Wurmser said, but the two will continue to split the Android market.

The amount that people are spending via proximity mobile payments is also on the rise. On average, a user will spend more than $1,500 on mobile payments, an increase of more than 24 percent compared to last year.

Masthead credit: Mobile payment by Kaspars Grinvalds