A quick check of Apple's (NASDAQ:AAPL) online store reveals something that at first glance might be alarming to Apple investors: The iPhone 8 and its larger sibling, the iPhone 8 Plus, are in ample supply just days after they became available. A SIM-free iPhone 8 Plus, for example, will ship in just one to three days. Ditto a SIM-free iPhone 8.

What this indicates is that Apple has largely achieved supply-to-demand balance within just a few days of availability -- an uncommon phenomenon for freshly released iPhones. Some have viewed this as a sign that demand for the new iPhones just isn't very good.

Apple's iPhone 8+ on the left and iPhone 8 on the right.

Image source: Apple.

While I think demand for the iPhone 8 and 8 Plus is down from the levels the iPhone 7 and 7 Plus enjoyed last year, I think supply is much better this year, too, which may be contributing to the ample availability of the devices.

Let's go over both factors.

iPhone X driving lower iPhone 8 and 8 Plus demand

There's a portion of the iPhone-buying population, probably a substantial portion, that wants to buy the best new iPhone. And that iPhone is neither the iPhone 8 nor the 8 Plus. It's the iPhone X (pronounced "iPhone ten"). Don't be surprised if those buyers pass on the iPhone 8 and 8 Plus and opt to wait for iPhone X sales to begin before throwing their hard-earned money at Apple.

Then there are those who'll wait because they find value in the additional features the iPhone X brings to the table. The iPhone X has a much more aesthetically pleasing industrial design than either the iPhone 8 or 8 Plus, thanks to the use of a stainless-steel frame and an extremely high screen-to-body ratio enabled by the full-face OLED display.

The Apple iPhone X.

Image source: Apple.

But it's not just appearances and form factor that set the iPhone X apart. The iPhone X has a superior rear-facing camera subsystem, a dramatically better front-facing camera subsystem with 3D sensing technology that Apple calls a "TrueDepth" camera, and support for new features such as Apple's animated emojis.

It's easy to imagine that many potential iPhone customers will be willing to wait a little longer and pay a little more to get what they perceive to be a better, more exciting product. Don't be surprised, then, if demand for the iPhone 8 and 8 Plus is down year over year as many customers wait for the iPhone X to become available.

More predictable supply

The iPhone 8 and 8 Plus do offer a lot of improvements over the prior-generation iPhone 7 and 7 Plus. Apple says the phones have new Retina displays with True Tone technology, faster processors, dramatically improved cameras, new glass-backed designs, support for wireless charging, and more.

It's all good stuff. On a personal note, I've been using the iPhone 8 Plus for a few days now and am highly impressed, coming from an iPhone 7 Plus. Nevertheless, I don't see anything in these phones that should be unusually hard to manufacture, outside of, perhaps, the new glass body.

The new displays appear to be enhanced versions of the displays that Apple has been producing for over a year in support of the iPhone 7-series phones, so it seems unlikely that display manufacturing could be a production show-stopper for the iPhone 8 series.

Apple's A11 Bionic chip is manufactured by Taiwan Semiconductor Manufacturing Company (NYSE:TSM) using the latter's new 10nm technology. During TSMC's July earnings call, co-CEO C.C. Wei told investors that the contract chipmaker had been "ramping up [its] 10-nanometer at full speed" for a month and that its manufacturing yield rates were "slightly ahead of schedule." So I don't see the A11 Bionic as being a potential production bottleneck for Apple, either.

I could go on, but the point is that the odds are good that the iPhone 8 and 8 Plus aren't unusually difficult to manufacture, in stark contrast to what the rumor mill says about the iPhone X. If the 8-series was easy to make, it could have allowed Apple to have ample supply of the devices shortly after they were announced.

So, is the iPhone 8 series a failure?

I can't imagine that the iPhone 8 series will go down as a failure. These are great phones that, if my experience with the iPhone 8 Plus is representative, would've made fine flagship devices from Apple had the iPhone X not been announced this year.

But to be clear, the iPhone 8 and 8 Plus probably weren't designed to be Apple's flagships. From what I can tell, they represent Apple's way of bringing much of the technology goodness inside the iPhone X to the market at price points that it simply couldn't get the iPhone X to fit in during this product cycle.

In that respect, I think the iPhone 8 and 8 Plus will prove highly successful, and Apple will still sell tens of millions of them over the next year.

Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has a disclosure policy.