Style isn't forever.

Apple (NASDAQ:AAPL) is not forever.

Even with its stock trading at less than half of its 52-week high, I'm not sure if the company's mortality is common knowledge. Even with the company offering guidance for the holiday quarter that at the low end implies a year-over-year dip in revenue, the Steve Jobs shrine glows with scented candles.

I'm a realist. I'm a historian. I'm here to tell you that coolness fades like henna tattoos, denim, and my childhood dream of flying to the moon. Apple is hot, but it won't be cool forever.

Z is for Zip
I've been writing for The Fool since 1995 and have been a member of the community since 1994, so I had front row seats to the Iomega revolution. The company may have bowed out quietly after being acquired by storage giant EMC (NYSE:EMC) earlier this year, but it was the cool kid in town when it introduced its Zip disks toward the end of 1994.

Iomega's stylish cobalt blue Zips were elegant and functional. With superior storage capacity to floppy diskettes, it became an essential PC accessory. Tape storage rival SyQuest tried to make its mark in the niche, but it was too late. Iomega was gobbling up market share and all of the style points.

We all know how it ended. Zip ultimately handed the baton to CD-Rs, flash memory cards, and USB drives.

A is for Apple
Apple is far more diversified than Iomega ever was, but the company's flagship Mac line was languishing until it rolled out the iPod. Where would Apple be today if it wasn't for that one introduction?

Apple has gained market share in 14 of the past 15 quarters, and it's hard to fathom that happening without the iPod's "halo effect" in its favor. Even the runaway success of its iPhone -- where it outsold market leader Research In Motion (NASDAQ:RIMM) during its most recent quarter -- would have been a challenge if it wasn't for the iPhone doubling as an iPod touch.

However, one can't dismiss the rare software duds in Apple's recent history or the slow adoption rate of its Apple TV gizmo. Maybe they are just lacking iPodiness. Maybe they are too far out of Apple's sweet spot. Maybe -- just maybe -- halos fade, too.

D is for Doh!
The Simpsons lampooned the aspirational Apple Store concept over the weekend. Having Matt Groening poke fun at a killer brand isn't necessarily a death sentence, though I do recall Starbucks (NASDAQ:SBUX) trading much higher when an animated Bart Simpson was walking through a Springfield shopping mall where every other store was a Starbucks.

None of this would matter if Apple wasn't arrogant. At least then it would be self-aware enough to recognize the cracks and rush in with the caulking gun. Unfortunately, Apple has been slow to pick up on its flaws.

iPod revenue in the latest quarter grew by just 3%. Sure, iPhone sales have donned cannibal suits there, but who is to say that the iPhone is eternal? Google's (NASDAQ:GOOG) open Android platform is going to carve out a slice. You also have RIM putting out more consumer-friendly BlackBerry products, and this morning's introduction of the cool Nokia (NYSE:NOK) N97. It should raise the smartphone bar with its widescreen touchscreen display, full QWERTY keyboard, and a five-megapixel camera that you can actually use to take great snapshots.

This brings us back to the company's refreshed MacBook line. Surely nothing can bring down the "I'm a Mac" crowds. Even last month's admission by Apple that Mac owners should load up on "multiple" antivirus programs -- after years of mocking PC makers for their hacking vulnerabilities -- won't get in the way. Right?

Well, let's see how those Macs are selling. I love to lean on (NASDAQ:AMZN) to get a pulse of where consumer tastes are heading. I pointed out how six of the nine top-selling products during a spot check early last December were MacBooks. This morning, Apple doesn't even crack the top five in portable computing. Netbooks are the hot sellers. Apple doesn't make them. It's sitting back and studying the market, but apparently doesn't know how to "make a $500 computer that isn't a piece of junk."

It's a big mistake for Apple to let a new, low-cost niche gobble up market share. At least Iomega tried its hand in putting out rewriteable CD drives. Apple is going to somehow believe that it can reach the masses with premium pricing, even in this soft economy. My friend Tim Beyers agrees with Apple's stance, but I don't.

Either way, even Apple's own guidance is pointing to the real possibility of lower revenue this year. That means that between iPods, Macs, and iPhones, one or more of those categories will be in decline.

So, is Apple the next Iomega? Will open source smartphones and netbooks be the CD-Rs and flash memory solutions that booted Iomega from the cool kids' table?

I'm worried, but what do I know? I'm still waiting for a cobalt blue iPhone.  

Marketing mantras on parade right here: