Fifteen million additional Apple (NASDAQ:AAPL) iPhone 6 sales... in the U.S. alone! How's that for humble pie?

Recently, I argued against the idea that Apple is working toward further segmenting its upcoming iPhone lineup by splitting the new iPhones into two different screen sizes, with one coming in a 4.7-inch size, plus another larger model with a 5.5-inch display. Given the mounting evidence that suggests to the contrary, however, I might just need to change my tune regarding Apple's design plans for the iPhone 6.

Source: Apple

A whole lotta iPhone6
Recently, Morgan Stanley equity research published the results of a survey, claiming that Apple could sell an incremental 15 million iPhone 6s if it indeed elects to produce a model with a screen size north of five inches, just in the U.S. That's truly incredible, but it's not the only recent data point that suggests Apple could make an absolute killing with a larger iPhone.

Another data set recently strengthened the argument that a larger-screened iPhone 6 could be a boon for Apple in key overseas markets like China, where some 40% of smartphones sold in April also had screen sizes larger than five inches.

So, personal design qualms aside, it seems like the business argument for Apple further segmenting its iPhone 6 lineup by screen size, as well as type (assuming the 5c survives), could prove an absolute boon for Apple investors, as tech and telecom specialist Andrew Tonner discusses in the video below.

Andrew Tonner owns shares of Apple. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.