An analyst with Jeffries & Co. recently published, by way of Barron's, some predictions about Apple's (NASDAQ:AAPL) 2018, 2019, and even 2020 iPhone lineups. I don't intend to go over those predictions or judge the likelihoods of each prediction given. Instead, I'd like to zero in on one specific prediction that the analyst made and explain why it's not likely to be correct.

About that 6.46-inch iPhone X...

Next year, Apple is expected to introduce a larger-screen member of the iPhone X family, which I'll refer to as the iPhone X Plus (2018) for simplicity. The device was previously rumored to feature an organic light-emitting diode (OLED) display -- a type of display technology that offers excellent contrast ratios and fast pixel response times, compared with what common liquid crystal displays are capable of.

The rumor also said the display would measure 6.46 inches along the diagonal. That would make the display the largest Apple has ever shipped on a smartphone.

An Apple iPhone 8 running an intensive 3D game.

Image source: Apple.

KGI Securities analyst Ming-Chi Kuo, whose track record in predicting the key specifications of upcoming Apple products is nothing short of excellent, recently claimed that the display on the iPhone X Plus (2018) will feature a pixel density -- a measure of how sharp a display is, so bigger is better -- of between 480 and 500 pixels per inch.

The analyst with Jeffries, on the other hand, thinks the iPhone X Plus (2018) will have a display with a pixel density of just 459 pixels per inch but that its successor, which should launch a year later in the second half of 2019, will get a display with a pixel density of 491 pixels per inch. That figure falls within the range Kuo gave.

That, in my view, doesn't fit in with Apple's past behavior.

Apple's iPhone X in Space Gray.

Image source: Apple.

Apple doesn't like pixel density changes

Apple tends to not make significant changes in the pixel densities or, frankly, the display resolutions of its displays unless they're accompanied by major form factor changes. For example, Apple's 4.7-inch and 5.5-inch iPhones didn't see display resolution increases over four product generations. Since the display sizes didn't change over that period, the pixel densities of those displays didn't change, either.

The same holds true for Apple's other product categories such as the iMac, MacBook Pro, and iPad: Once Apple decides on certain display sizes and pixel densities, it tends to stick with them. Apple chooses these sorts of things quite carefully.

Given Apple's history, I can't see the company introducing the iPhone X Plus (2018) with a certain display resolution and pixel density and then introducing an iPhone X Plus (2019) with the same size screen but with a resolution and pixel density increase.

I believe Kuo has this one right and that the iPhone X Plus (2018) will feature a jumbo-sized OLED display that's even sharper than the one found on this year's iPhone X.

A more likely cadence of improvements

Apple aims to deliver technology enhancements that meaningfully enhance the user experience. To that end, I think Apple will decide on a certain display resolution for the jumbo-sized iPhones with OLED displays and then stick with it for several generations.

That's not to say, though, that Apple won't deliver display innovations over time. For example, Apple is probably going to look to boost the brightness of future iPhone X and X Plus displays, and I'm sure the company's engineers are hard at work at bringing the amazing ProMotion technology currently found on the company's iPad Pro series of tablets to future iPhones as well.

These improvements would be far more interesting than, say, continuing to push resolution and pixel density upward in future devices.

Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has the following options: long January 2020 $150 calls on Apple and short January 2020 $155 calls on Apple. The Motley Fool has a disclosure policy.