Fresh data coming from IDC and App Annie says that both Apple and Google are likely to see their app store revenues double within the next four years. Apple’s 2014 total revenue constituted $10B in 2014, so this would mean that Apple could hit total revenue of around $20 billion in 2018. Developers would get $14B of it and Apple would be left with the remaining $6 billion.
Speaking with Recode, App Annie CEO Bertrand Schmitt said the following: “I would consider this projection conservative.” Therefore, don't be surprised if the actual numbers turn out to be even bigger. Recode points out that the same study found that revenue from both sources grew at a similar rate from 2013 to 2014, expanding 1.7 times.
The report only takes in account sales from Apple and Google’s marketplaces, excluding Amazon and Microsoft’s digital stores as well as other third-party stores. Ina Fried with the publication further adds:
"While the study didn’t offer absolute dollars to go with its growth figures, Apple has said that its App Store generated $10 billion in revenue to developers last year, while Google has said it has paid out $7 billion to app developers over the past 12 months."