Image source: Apple. 

In a discussion thread over at Apple (AAPL 0.31%)-focused website Apple Insider, a user made a curious comment regarding the iDevice maker's next-generation iPhone, widely expected to be called the iPhone 7.

The user asked, "what is so 'highly anticipated' about the iPhone 7?" The poster went on to argue that "we've reached a point with the iPhone 6s where the phone is so good, that improving upon it in any meaningful way is...difficult."

If this individual's argument held true, then it would indeed be bad news for Apple as upgrade cycles would likely lengthen fairly significantly. 

However, as somebody who owns both the iPhone 6s and iPhone 6s Plus, I can say the avenues of meaningful improvement from here on out remain blindingly obvious. Here are a few that spring to mind.

The displays
The displays on Apple's latest iPhones are good, but they are far-and-away from perfect. They lag in many important ways relative to some flagship Android devices (i.e. Galaxy S6) such as in color accuracy, contrast ratio, and many other key metrics -- at least according to highly respected display analysis expert Raymond Soneira of Display Mate.

With the iPhone 7, I expect Apple to deliver a substantial boost in display quality that will be immediately obvious to anybody who compares the two devices side-by-side.

In addition to improvements in image quality, I expect Apple to finally up the ante in terms of display resolution. Apple's premium flagships have less sharp displays than some mid-range devices that are currently on the market!

Additionally, since Apple probably won't transition to OLED-based displays until at least the iPhone 7s (but more likely the iPhone 8), there's still at least one more "low hanging" fruit beyond iPhone 7 that Apple can capture as far as iPhone displays go.

The cameras
The cameras on the iPhone 6s/6s Plus are good for smartphone cameras, but there is a long way for them to go before they are anywhere close to being able to capture images anywhere near the quality of a reasonable DSLR. I believe that smartphone users -- particularly premium phone users -- value camera image quality.

Innovations along this particular vector (which will require some heavy-duty engineering in sensor design, optics, and in the image signal processor embedded in the company's A-series chips) should pay off nicely in terms of selling points.

Industrial design
Apple prides itself on its industrial designs and for good reason: Many folks view their devices as "status symbols" and it wouldn't be surprising if many phone users base purchasing decisions at least partially on visual appearance, texture, and the other elements that make up the "look and feel" of the device.

Additionally, there's still plenty of room for the iPhone to become slimmer and more compact, even given the same screen real estate. Many reviewers criticized the iPhone 6 Plus/iPhone 6s Plus devices as being simply too "unwieldy" even for 5.5-inch devices.

I share the popular view that Apple should focus on slimming down the bezels on its phones (both the top and side ones) in order to reduce the physical footprints of its devices. Doing so should lead to better scores and sentiment in third-party reviews of the devices, potentially helping the iDevice maker to catalyze upgrades and maybe even gain share.

Although there will come a time when iPhone upgrades will really seem "incremental" and may even be underwhelming generation-over-generation (though Tim Cook reportedly told employees that he sees iPhone growth for "decades"), I don't think we're there just yet. 

The iPhone is still an extremely imperfect device, with plenty of obvious avenues of improvement for Apple to pursue. This comment isn't mean to disparage Apple, but to express my optimism that the iDevice maker may still have plenty of tricks up its proverbial sleeve to allow Apple to actually grow sales of this product category for years to come.