Apple will reportedly introduce the iPhone 6 with a 4.7-inch display this August, and will follow up with a 5.5-inch model in September, according to industry sources claiming to have inside information about the company's plans. If true, Apple would be updating the iPhone lineup a month earlier than expected.
The sources, according to Reuters, come from Apple's parts supply chain. Those sources also claim the company plans to build 80 million iPhone handsets this year.
While supply chain sources may have some level of insider access to Apple, they typically get a very small glimpse into the company's plans since they're providing individual components instead of finished products. Apple doesn't have any reason to divulge its overall plans with suppliers, which means they're often trying to extrapolate what the company is up to from a single data point.
Rumors about larger screen iPhones are easy to come by right now, and most settle on either 4.7-inch, 5.5-inch and 5.7-inch displays. Reports seem to be settling more on the 4.7-inch display, with a 5.5-inch model possibly following soon after, or even some time in 2015.
Apple already supports two iPhone screen sizes: 4-inch on the iPhone 5S and iPhone 5C, and 3.5-inches on the iPhone 4S. Presumably, the smaller screen will go away when the iPhone 4S is retired, and that will likely happen when the iPhone 6 is introduced. Assuming Apple goes with a 4.7-inch screen for the new model, that still leaves the 4-inch display in service, making for two sizes developers will need to support. Adding a third size doesn't sound like an Apple move.
Since Apple doesn't talk about unannounced products, we're left to speculate about what's really in store for the iPhone. Right now, it safe to say Apple is working on an updated model, and it's likely to come with a larger display. Adding two screen sizes seems less likely since that could create confusion in the product line and make coding for the different displays more difficult.