A little while back, an interesting rumor surfaced about Apple's (NASDAQ:AAPL) next-next iPhone series, which I'll refer to as the iPhone 9.

The rumor, published by The Bell and reported on by MacRumors, said the iPhone 9 models will come in two display sizes: 5.28 inches and 6.46 inches. And naturally, both of the displays will be organic light emitting diode (OLED) displays, rather than the liquid crystal displays used on the current iPhone 7-series models.

Apple's iPhone 7 Plus lineup.

Image source: Apple.

Now, if we combine this rumor with a recent report from Nikkei Asian Review that Apple is planning to launch not two, but three iPhone models next year, all with OLED displays, next year, the iPhone 9 lineup seems to come into sharply into focus.

Small, standard, and large

Apple's smallest smartphone, the iPhone SE, could get a significant size boost, from a 4-inch display to 5.28 inches. While it might seem as though changing a small phone to a big one would ruin the whole point of the iPhone SE, I don't think that'd be the case.

Remember: The iPhone SE's design has a poor screen-to-body ratio by today's standards. The top and bottom bezels take up a lot of space on the front of the device, and even the side bezels are quite large. Apple could fit quite a lot of screen in the same physical footprint as the iPhone SE if it transitions to a full-face 18:9 aspect-ratio display with virtually no bezels. The home button, in this case, would be replaced with a virtual home button, as is rumored to be happening with this year's iPhone 8.

Then, for the middle version of the iPhone 9 lineup, Apple could stick with a 5.8-inch display. It would be extremely unusual for Apple to adopt a display size for one generation and then simply abandon it altogether. That's why the rumor that Apple is planning just 5.28- and 6.46-inch iPhone 9 models doesn't pass a sanity test, but planning those two screen sizes in addition to this year's 5.8-inch size makes a lot of sense.

And, finally, Apple could do a 6.46-inch iPhone for customers who didn't mind, or maybe even preferred, the physical footprint of the 5.5-inch iPhone and would like to have even more screen real estate. Such a device probably wouldn't be as popular as the 5.8-inch middle model, but there are quite a few smartphone power users out there who would appreciate using such a large screen -- and they'd probably be willing to pay a handsome premium for the luxury.

Further, since Apple might be able to charge a pretty hefty sum for this device, as it would be Apple's highest-end smartphone at launch, it could do double duty as a "special edition" phone that incorporates features and technologies that simply couldn't be included in the lower-priced, higher-volume 5.8- and 5.28-inch models.

Apple's coming product cycle should be quite nice for the company's iPhone average selling prices, but Apple will have to work hard to maintain them. This approach would help the company keep its iPhone average selling prices relatively high for the next-next iPhone cycle.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.