The difference between the tech rumor mill and reality that we inhabit is that the world of fantasy is one devoid of constraints. Sitting behind a keyboard it is possible to dream up a myriad of magical devices that operate outside of the laws of physics.
The motto is, "if you can dream it, then it must be possible."
However, back in the real world, things are a lot more reserved. Devices have to operate within the limitations of the laws of physics, and Apple's upcoming iPhone 6 is no different. While Apple would like us to believe that its devices are magical, the truth is they are not.
Building a successful consumer electronics device involves delicately balancing four interconnected variables.
Let us take a look at each one of these variable in turn.
I'm going to start with what I see as the most important variable – power.
Mobile devices rely on their built-in battery, and everything the device does draws on this. While the biggest power draws are going to be the display, the processor and the radios, everything the device does sucks on the battery, and no matter how small the energy consumption, milliamps quickly add up.
When it comes to an updated iPhone, faster processors, bigger displays, better cameras, faster wi-fi and cellular, and more stuff happening in the background all put an additional strain on the battery. On the upside, as technology gets smaller, the power requirements do go down slightly.
Now in an ideal world, Apple could just bolt a giant battery onto the iPhone and not worry about power drain, but that would have a detrimental effect on usability. The trend is towards lighter and thinner devices, and this severely limits the space left for a battery.
Rumors that Apple might be getting ready to bump up the iPhone's screen to 4.7-inch or even 5.5-inch might seem bad for battery life, because a larger display means a greater demand for power. However, a larger display means more internal space for the battery, assuming thickness is unchanged. A larger screen could even pave the way for a thinner iPhone 6 while still leaving more volume for a larger battery.
The bottom line is that every milliamp has to be accounted for, and there's no room for overenthusiastic engineering.
Everyone wants their new iPhone to do more than their old iPhone did, and this means cramming it with faster hardware. But faster hardware puts a pressure on power and price, so the sky isn't the limit here.
Another factor to consider when it comes performance is that Apple tightly controls the iOS ecosystem, can engineer the iPhone to offer performance that will keep it relevant for the next three years or so without having to over-engineer the hardware. There's also little point in stuffing the iPhone 6 with power components that the software cannot utilize.
So the trick is to make it better than the last version, pack it with features that will keep it in the game for the next few years, but at the same time not waste money or battery life on making it too powerful.
Since the final product has to be usable, this means having adequate performance and battery life without having to resort to carrying the battery in a backpack. It also means building a device that's ergonomic and easy to use.
A lot of the iPhone 6 rumors have pointed to the fact that Apple is once again getting ready to bump up the screen size of the iPhone. The original iPhone shipped with a 3.5-inch display, which Apple initially said was the perfect size for using the handset single-handedly. This was increased to 4-inch with the iPhone 5, again with claims from Apple that this still allowed for single-handed use. If Apple does indeed bump the screen size to 4.7-inches and beyond, then it will be interesting to see if/how Apple addresses the issue of usability.
Devices have to be built to a tight budget, especially given that overspending by a few cents can quickly mount up to hundreds of millions of dollars.
With the iPhone Apple is treading a thin line where it is designing and manufacturing a mass market device but making it feel like a customized, bespoke item. It is in essence building something to be marketed as a luxury item, but without the crazy pricing of luxury items such as high-end wristwatches and sports cars.
Apple has more wriggle room than most companies give its buoyant +30 percent margin, but it would be reckless and foolhardy to start eating away at this to create a "better" iPhone because it's hard to stop doing this down the line as consumers demand more and more for their money.
The bottom line
The iPhone 6 will be evolutionary rather than revolutionary. It will build on the current iPhone platform and offer a platform that will remain relevant for the next few years. Remember that when pundits are criticizing the iPhone 6 for not being good enough.
Apple already sells iPhones as fast as it can make them almost, so Apple only needs to make a better iPhone, not one that's revolutionarily better. And that "better iPhone" will be the fruits of engineers at Apple carefully balancing out the variables I've outlined above.